Abstract

The objective of this study was to evaluate the use of drugs and the factors associated with polypharmacy in patients with diabetes mellitus (DM) in Minas Gerais. Descriptive analysis of drugs in use and logistic regression to estimate the association between socio-demographic and clinical characteristics with polypharmacy were performed. Of the 2619 respondents, 56.5% were in polypharmacy. Drugs for DM, agent in renin-angiotensin system, and diuretics are the most frequently used. Factors such as age, comorbidities and increased access to health services were associated with polypharmacy. It was observed high prevalence of polypharmacy, which requires a suitable care and better quality of drug use in this population.

Diabetes mellitus; Drug utilization; Polypharmacy; Pharmacoepidemiology

Introduction

Diabetes Mellitus (DM) is a chronic complex disease, which requires continuous medical assistance and the use of multifactorial strategies for risk reduction, besides the search for glycemic control¹1. American Diabetes Association. Standart of Medical Care in Diabetes. Introduction. Diabetes Care 2016; 39(Supl. 1):S1-S2.. It is presented as a worldwide epidemic, representing a great challenge for the health systems all over the world²2. Sociedade Brasileira de Diabetes. Diretrizes da Sociedade Brasileira de Diabetes. 2014-2015. São Paulo: AC Farmacêutica; 2015.,³3. Wild S, Roglic G, Green A, Sicree R, King H. Global prevalence of diabetes: estimates for the year 2000 and projections for 2030. Diabetes Care 2004; 27(5):1047-1053..

The world prevalence of DM is estimated in 387 million people and is expected an increase to 592 million people for the coming year of 2035, between 20 and 79 years old⁴4. International Diabetes Federation. Diabetes atlas. 6th ed. 2014 Update. [acessado 2015 Mar 11]. Disponível em: http://www.idf.org/sites/default/files/Atlas-poster-2014_EN.pdf
http://www.idf.org/sites/default/files/A... . In Brazil, the DM prevalence achieves 8.7% of the population above 20 years old, which corresponds to 11.6 million people. Out of this portion, 3.2 million would be undiagnosed⁵5. International Diabetes Federation. Diabetes atlas. 6th ed. 2014 Update. [acessado 2015 Mar 11]. Disponível em: http://www.idf.org/sites/default/files/6th-Edition-Estimates_Update_2014.xls
http://www.idf.org/sites/default/files/6... .

About 75% of type 1 DM cases are diagnosed in individuals with age lower than 18 years. Besides, an incidence of type 2 DM is estimated in 2.3% a year in individuals with age lower than 20 years; a proportion that will increase significantly the prevalence of this disease in this age group of the population⁶6. American Diabetes Association (ADA). 11. Children and Adolescents. Diabetes Care 2016 Jan; 39(Supl. 1):S86-S93..

On the other hand, it is being configured as an important health condition in the aging process, as 26% of patients aged above 65 years has DM, and this number should increase quickly in the next decades. The older individuals with diabetes have higher rates of early death, functional inability, and coexisting diseases than individuals without DM⁷7. American Diabetes Association (ADA). 10. Older Adults. Diabetes Care 2016; 39(Supl. 1):S81-S85., and it takes to a decrease in their quality of life⁸8. Mata AR, Álvares J, Diniz LM, Silva MRR, Santos BRA, Guerra Júnior AA, Cherchiglia ML, Andrade EI, Godman B, Acurcio FA. Quality of life of patients with Diabetes Melito Types 1 and 2 from a referal health centre in Minas Gerais, Brazil. Expert Rev Clin Pharmacol 2016; 9(5):739-746..

In this context, patients with DM have a higher risk to present polypharmacy than other patients⁷7. American Diabetes Association (ADA). 10. Older Adults. Diabetes Care 2016; 39(Supl. 1):S81-S85.,⁹9. Freeman JS, Gross B. Potential drug interactions associated with treatments for type 2 diabetes and its comorbidities: a clinical pharmacology review. Expert Rev Clin Pharmacol 2012; 5(1):31-42., and this phenomenon is defined by most of the studies as the simultaneous use of five or more medications¹⁰10. Qato DM, Wilder J, Schumm LP, Gillet V, Alexander GC. Changes in Prescription and Over-the-Counter Medication and Dietary Supplement Use Among Older Adults in the United States, 2005 vs 2011. JAMA Intern Med 2016; 176(4):473-482.

11. Carvalho MF, Romano-Lieber NS, Bergsten-Mendes G, Secoli SR, Ribeiro E, Lebrão ML, Duarte YA. Polypharmacy among the elderly in the city of São Paulo, Brazil - SABE Study. Rev Bras Epidemiol 2012; 15(4):817-827.-¹²12. Viktil KK, Blix HS, Moger TA, Reikvam A. Polypharmacy as commonly defined is an indicator of limited value in the assessment of drug-related problems. Br J Clin Pharmacol 2007; 63(2):187-195.. The prevalence of polypharmacy in elderly in the United States has increased significantly, from 30.6% to 35.8%, and the risk for major drug interaction has increased from 8.4% to 15.1%, in a period of five years. These results become even more relevant when the consumption of food supplements in this population is observed, as vitamins and omega 3, which suggests the necessity of greatest care and follow-up of the patients using multiple medications and having chronic diseases¹⁰10. Qato DM, Wilder J, Schumm LP, Gillet V, Alexander GC. Changes in Prescription and Over-the-Counter Medication and Dietary Supplement Use Among Older Adults in the United States, 2005 vs 2011. JAMA Intern Med 2016; 176(4):473-482.. It is observed, therefore, an increasing worry with polypharmacy and its impact on the morbidity, mortality, and the costs related to patient and Healthcare Services¹³13. Marković-Peković V, Škrbić R, Petrović A, Vlahović-Palčevski V, Mrak J, Bennie M, Fadare J, Kwon HY, Schiffers K, Truter I, Godman B. Polypharmacy among the elderly in the Republic of Srpska: extent and implications for the future. Expert Rev Pharmacoecon Outcomes Res 2016; 16(5):609-618..

Recent studies in different populations of DM patients have evaluated the disease prevalence¹⁴14. Vitoi NC, Fogal AS, Nascimento CM, Franceschini SD, Ribeiro AQ. Prevalence and associated factors of diabetes in the elderly population in Viçosa, Minas Gerais, Brazil. Rev Bras Epidemiol 2015; 18(4):953-965

15. Moraes SA, Freitas IC, Gimeno SG, Mondini L. Diabetes melito prevalence and associated factors in adults in Ribeirão Preto, São Paulo, Brazil, 2006: OBEDIARP Project. Cad Saude Publica 2010; 26(5):929-941.

16. Sharma M, Nazareth I, Petersen I. Trends in incidence, prevalence and prescribing in type 2 diabetes melito between 2000 and 2013 in primary care: a retrospective cohort study. BMJ Open. 2016; 6(1):e010210. Erratum in: BMJ Open 2016; 6(5):e010210corr1.

17. Andersson T, Ahlbom A, Carlsson S. Diabetes Prevalence in Sweden at Present and Projections for Year 2050. PLoS One 2015; 10(11):e0143084.-¹⁸18. Meo SA. Prevalence and future prediction of type 2 diabetes melito in the Kingdom of Saudi Arabia: A systematic review of published studies. J Pak Med Assoc 2016; 66(6):722-725. and demonstrated its increase in the last decades, with estimations indicating that such increase will remain over the years¹⁶16. Sharma M, Nazareth I, Petersen I. Trends in incidence, prevalence and prescribing in type 2 diabetes melito between 2000 and 2013 in primary care: a retrospective cohort study. BMJ Open. 2016; 6(1):e010210. Erratum in: BMJ Open 2016; 6(5):e010210corr1.

17. Andersson T, Ahlbom A, Carlsson S. Diabetes Prevalence in Sweden at Present and Projections for Year 2050. PLoS One 2015; 10(11):e0143084.-¹⁸18. Meo SA. Prevalence and future prediction of type 2 diabetes melito in the Kingdom of Saudi Arabia: A systematic review of published studies. J Pak Med Assoc 2016; 66(6):722-725.. Other studies have reported that the number of medications in use is elevated¹⁴14. Vitoi NC, Fogal AS, Nascimento CM, Franceschini SD, Ribeiro AQ. Prevalence and associated factors of diabetes in the elderly population in Viçosa, Minas Gerais, Brazil. Rev Bras Epidemiol 2015; 18(4):953-965,¹⁹19. Bauer S, Nauck MA. Polypharmacy in people with Type 1 and Type 2 diabetes is justified by current guidelines - a comprehensive assessment of drug prescriptions in patients needing inpatient treatment for diabetes-associated problems. Diabet Med 2014; 31(9):1078-1085.,²⁰20. Pereira VO, Acurcio FA, Guerra Júnior AA, Silva GD, Cherchiglia ML. Use of medicines by individuals with hypertension and diabetes in municipalities covered by the Pharmacy Network in Minas Gerais State, Brazil. Cad Saude Publica 2012; 28(8):1546-1558.. However, studies evaluating the factors associated to polypharmacy in the DM populations have not been observed. So, this study has as purpose to evaluate the polypharmacy prevalence and its associated factors, describing also the profile of medications utilization in DM patients in Minas Gerais, Brazil.

Methods

Sample

A household survey was realized in 63 municipal areas of Minas Gerais, being 61 inland municipalities, the State capital Belo Horizonte, and Contagem, between January and February of 2014. All these cities possessed pharmaceutical services structured and functioning. The criteria for the selection by convenience of the inland cities were: urban population higher than two thousand inhabitants; ‚ to have a unit of the State Pharmacy (Rede Farmácia de Minas) in activity at least 2 years; ƒ to possess access to internet in the service; to present consent from the Municipal Health Secretary, and manifestation of interest to be participating in the project, expressed by the local pharmacist. The study population was composed of individuals bearing DM, without any restriction, who agreed to participate and signed the Informed Consent Form. The selected municipal areas are part of all the 13 health macro-regions of the Minas Gerais.

The sample for every municipal area has been selected randomly, considering the census sectors adopted by the Brazilian Institute of Geography and Statistics (IBGE) for the respective urban perimeter. The investigators received localization maps referring to each selected sector, which were walked house by house, without return in case of absent dweller, according to the following groupings: a) for Belo Horizonte and Contagem, with populations of 2.4 million and 650 thousand inhabitants²¹21. Instituto Brasileiro de Geografia e Estatística (IBGE). Estimativas de população para 1º de julho de 2013. Rio de Janeiro; IBGE; 2013. [acessado 2015 Ago 14]. Disponível em: http://www.ibge.gov.br/home/estatistica/populacao/estimativa2013/estimativa_tcu.shtm
http://www.ibge.gov.br/home/estatistica/... , respectively, 122 and 25 census sectors were selected; b) for municipal areas with urban population higher than 5,000 inhabitants and a minimum of ten census sectors of IBGE, five sectors were drawn; c) for municipal areas with urban population between 2,000 and 5,000 inhabitants and with less than ten IBGE census sectors, all possible houses were visited.

The sample size calculation was executed considering the DM prevalence of 8.7% over the reference population of Minas Gerais in 2013, which was of 20.593.366 inhabitants²¹21. Instituto Brasileiro de Geografia e Estatística (IBGE). Estimativas de população para 1º de julho de 2013. Rio de Janeiro; IBGE; 2013. [acessado 2015 Ago 14]. Disponível em: http://www.ibge.gov.br/home/estatistica/populacao/estimativa2013/estimativa_tcu.shtm
http://www.ibge.gov.br/home/estatistica/... ; corresponding to the estimation of 1,791,623 individuals with DM, a level of confidence of 95%, estimated prevalence of 50% for different outcomes of prevalence, maximal tolerated error of 2%. Taking as a base these parameters, the minimal final sample was estimated in 2,398 individuals, to which a margin of 10% was added to cover possible losses. Then, a total of 2,638 individuals should be interviewed.

Study variables

The dependent variable was the occurrence of polypharmacy, defined as the use of five or more medications; an information that was obtained from the question: In the last 15 days, have you utilized medications?. The response to this question should be proven by means of the respective package presentation or medical prescription.

The independent variables were sex, age group, marital status, schooling, race, health self-perception, self-reported DM type, average time of DM diagnosis, number of self-reported comorbidities, frequency of medical consultations in the last year, public or private health plan, regular practice of physical activity, and interruption of normal activities in the last 15 days.

Data analysis

The descriptive analysis was developed by means of the distribution of frequencies of medications in use, according to anatomical therapeutic classification (ATC) in first, second, and fifth level for the entire sample. For the variable number of medications, the average and standard deviation (SD) were obtained.

The factors associated to polypharmacy were analyzed, being constituted two comparison groups: without polypharmacy (reference group), defined as the use of zero to four medications, and polypharmacy, defined as the use of five or more medications. A bivariate analysis has been developed for comparison of frequencies, being utilized the Pearson’s chi-squared test. Were included in the multivariate analysis the variables that presented p-value < 0.20 in the bivariate analysis, utilizing the model of multiple logistic regression. Only the variables with the p-value < 0.05 remained in the final model. The data analysis was executed utilizing the software SPSS^® version 22.0.

Ethical considerations

The Independent Ethics Committee of the Federal University of Minas Gerais has approved the study.

Results

A total of 2,619 persons with DM was interviewed, being that 2,192 (83.7%) stated to have type 2 DM and 272 (10.4%) to have type 1 DM. Around 6% did not know to report about their DM type. The average age was 61.3 ± 16.4 years. The average time of DM diagnosis was of 9.9 ± 8.8 years.

When considering all study participants, a consumption of 13,629 medications was reported for the treatment of several diseases, with an amplitude of 0 to 17 medications in use per person, according to Graphic 1. The average number of medications utilized was of 5.2 ± 2.9.

About 60% of medications were acquired in public pharmacies and 35% were generic. The drugs with action on the cardiovascular system were the most utilized, followed by drugs with action in the alimentary tract and metabolism, and in the nervous system. The more frequent therapeutic classes in use were medications utilized for DM, agents acting in the renin-angiotensin system, the diuretics, lipid modifier agents, and thrombolytic agents. The more frequent medications in use were metformin, losartan, glibenclamide, and simvastatin (Table 1). These results correspond to the more prevalent comorbidities observed in the study, which were hypertension, with 76%; dyslipidemia, with 44%; and obesity, with 32%. In addition, 31% of patients reported that have or have had depression; and an important participation of antidepressants was observed among the agents actuating in the nervous system.

Among the interviewed persons, 56.5% – error margin in the CI 95% corresponding to 3.4% – were in polypharmacy. The group of polypharmacy presented higher frequency of female sex, with more advanced age and more time of diagnosis as compared with the group without polypharmacy. A larger number of comorbidities associated to DM, medical consultations in the last year, and interruptions of normal activities were verified in this group, in addition to lower regular practice of physical activity and worst self-perceived health. All these variables showed statistical significance in their association with polypharmacy in the bivariate analysis (Table 2).

The analysis of logistic regression indicated that the factors associated positively and significantly to the occurrence of polypharmacy in DM patients are age above 40 years, bad or very bad self-perceived health, presence of five or more comorbidities, average time of diagnosis above 10 years, four or more medical consultations in the last year, absence of regular physical activity, interruption of normal activities in the last 15 days, and access to a private health plan. (Table 3).

Discussion

The prevalence of polypharmacy in this study, considered as using five or more medications, was of 56.5%. According to literature, the occurrence of polypharmacy in DM patients in Brazil varies from 26.7% to 46.3%, proportions lower than the one found in our study¹⁴14. Vitoi NC, Fogal AS, Nascimento CM, Franceschini SD, Ribeiro AQ. Prevalence and associated factors of diabetes in the elderly population in Viçosa, Minas Gerais, Brazil. Rev Bras Epidemiol 2015; 18(4):953-965,¹⁵15. Moraes SA, Freitas IC, Gimeno SG, Mondini L. Diabetes melito prevalence and associated factors in adults in Ribeirão Preto, São Paulo, Brazil, 2006: OBEDIARP Project. Cad Saude Publica 2010; 26(5):929-941.,²²22. Araújo MF, Santos Alves PJ, Veras VS, Araújo TM, Zanetti ML, Damasceno MM. Drug interactions in Brazilian type 2 diabetes patients. Int J Nurs Pract 2013; 19(4):423-430.. An Indian study reports a prevalence of polypharmacy in type 2 DM individuals of 25.5% in younger patients and 41.6% in older patients²³23. Shastry R, Prabha Adhikari MR, Sheetal U, Kotian S. Comparison of polypharmacy between geriatric and nongeriatric diabetic patients. Int J Pharm 2016; 6(1):85-87.. Qato et al.¹⁰10. Qato DM, Wilder J, Schumm LP, Gillet V, Alexander GC. Changes in Prescription and Over-the-Counter Medication and Dietary Supplement Use Among Older Adults in the United States, 2005 vs 2011. JAMA Intern Med 2016; 176(4):473-482. have demonstrated a significant increase of polypharmacy prevalence between elderly within an interval of five years, which was associated mainly to an increase in the consumption of alimentary supplements and multiple prescriptions of medications in patients with comorbidities.

Another aspect, related to increasing of polypharmacy, results from the fact that individuals with DM are more prone to be in polypharmacy situation⁷7. American Diabetes Association (ADA). 10. Older Adults. Diabetes Care 2016; 39(Supl. 1):S81-S85.,¹²12. Viktil KK, Blix HS, Moger TA, Reikvam A. Polypharmacy as commonly defined is an indicator of limited value in the assessment of drug-related problems. Br J Clin Pharmacol 2007; 63(2):187-195.. This could be partially explained by the increase in the dose of in-use medications or the prescription of new medications, when the adherence to proposed treatment and the adequate control of DM and comorbidities are not achieved²⁴24. Pereira LRL, Andrade RCG, Pereira JGC, Marchetti JM. Avaliação de prescrições de medicamentos para pacientes com Diabetes Melito atendidos por uma Unidade Básica de saúde. Rev. Ciênc. Farm. Básica Apl. 2005; 26(3):199-203.,²⁵25. Jarab AS, Almrayat R, Alqudah S, Thehairat E, Mukattash TL, Khdour M, Pinto S. Predictors of non-adherence to pharmacotherapy in patients with type 2 diabetes. Int J Clin Pharm 2014; 36(4):725-733.; which could lead to a higher risk of drug interactions.

The medications acting on the cardiovascular system were the most utilized ones, followed by medications acting in the alimentary tract and metabolism, and nervous system, as observed in the studies developed by Pereira et al.²⁰20. Pereira VO, Acurcio FA, Guerra Júnior AA, Silva GD, Cherchiglia ML. Use of medicines by individuals with hypertension and diabetes in municipalities covered by the Pharmacy Network in Minas Gerais State, Brazil. Cad Saude Publica 2012; 28(8):1546-1558. in hypertensive and diabetic patients, and by Baldoni et al.²⁶26. Baldoni AO, Ayres LR, Martinez EZ, Dewulf NLS, Santos V, Obreli-Neto PR, Pereira RLR. Pharmacoepidemiological profile and polypharmacy indicators in elderly outpatients. Braz. J. Pharm. Sci. 2013; 49(3):443-452. in elderly. Bauer Nauck¹⁹19. Bauer S, Nauck MA. Polypharmacy in people with Type 1 and Type 2 diabetes is justified by current guidelines - a comprehensive assessment of drug prescriptions in patients needing inpatient treatment for diabetes-associated problems. Diabet Med 2014; 31(9):1078-1085. have identified that the medications most utilized by DM patients, within a center specialized in the treatment of DM in Germany, were those addressed to alimentary tract and metabolism, followed by those utilized for the cardiovascular system and nervous system. In the study of Guidoni et al.²⁷27. Guidoni CM, Borges AP, Freitas O, Pereira LR. Analysis of treatment of comorbidities and the profile of medical consultations for diabetes melito. Cien Saude Colet 2013; 18(10):3015-3022., the medications most utilized by patients with DM were those for the cardiovascular system, nervous system, blood and hematopoietic organs, and alimentary tract and metabolism. In other studies, with elderly patients, the most utilized drugs were those for the cardiovascular and nervous systems, and the alimentary tract and metabolism¹⁴14. Vitoi NC, Fogal AS, Nascimento CM, Franceschini SD, Ribeiro AQ. Prevalence and associated factors of diabetes in the elderly population in Viçosa, Minas Gerais, Brazil. Rev Bras Epidemiol 2015; 18(4):953-965,¹⁵15. Moraes SA, Freitas IC, Gimeno SG, Mondini L. Diabetes melito prevalence and associated factors in adults in Ribeirão Preto, São Paulo, Brazil, 2006: OBEDIARP Project. Cad Saude Publica 2010; 26(5):929-941.. In general, the similarity between utilized medications is due to more prevalent comorbidities associated to DM, hypertension, dyslipidemia, and depression, also observed in our study²2. Sociedade Brasileira de Diabetes. Diretrizes da Sociedade Brasileira de Diabetes. 2014-2015. São Paulo: AC Farmacêutica; 2015.,²⁸28. American Diabetes Association (ADA). 8. Cardiovascular Disease and Risk Management. Diabetes Care 2016; 39(Supl. 1):S60-S71..

According to American Diabetes Association (ADA), hypertension and dyslipidemia are commonly found in patients with DM that present, also, higher prevalence of depression than the people without DM; and this could difficult the treatment management of patients²⁸28. American Diabetes Association (ADA). 8. Cardiovascular Disease and Risk Management. Diabetes Care 2016; 39(Supl. 1):S60-S71.,²⁹29. American Diabetes Association (ADA). 3. Foundations of Care and Comprehensive Medical Evaluation. Diabetes Care 2016; 39(Supl. 1):S23-S35.. There is strong evidence that depression in people with diabetes increases the risk for complications related to this disease. The depression has been associated with hypoglycemia, to complications related to DM, as well as to the perception of functional limitations resulting from the DM²2. Sociedade Brasileira de Diabetes. Diretrizes da Sociedade Brasileira de Diabetes. 2014-2015. São Paulo: AC Farmacêutica; 2015.,²⁹29. American Diabetes Association (ADA). 3. Foundations of Care and Comprehensive Medical Evaluation. Diabetes Care 2016; 39(Supl. 1):S23-S35..

The more frequent therapeutic classes were the medications utilized in diabetes, agents acting on the renin-angiotensin system, the diuretics, and lipid modifier agents; corroborated by the studies of Guidoni et al.²⁷27. Guidoni CM, Borges AP, Freitas O, Pereira LR. Analysis of treatment of comorbidities and the profile of medical consultations for diabetes melito. Cien Saude Colet 2013; 18(10):3015-3022. and Bauer and Nauck¹⁹19. Bauer S, Nauck MA. Polypharmacy in people with Type 1 and Type 2 diabetes is justified by current guidelines - a comprehensive assessment of drug prescriptions in patients needing inpatient treatment for diabetes-associated problems. Diabet Med 2014; 31(9):1078-1085.. The hypertension treatment in patients with DM, suggested by ADA and by the IV Brazilian Guidelines on Hypertension, should include angiotensin converter enzyme inhibitor or antagonist of angiotensin receptor and, if the use of such agents is impossible, the application of diuretics, which was observed in this present study²⁸28. American Diabetes Association (ADA). 8. Cardiovascular Disease and Risk Management. Diabetes Care 2016; 39(Supl. 1):S60-S71.,³⁰30. Sociedade Brasileira de Cardiologia. VI Diretrizes Brasileiras de Hipertensão. Arq Bras Cardiol 2010; 95(1):1-51..

Among the most utilized medications according to ATC classification, only glimepiride and sertraline are not available in the Unified Health System (SUS)³¹31. Minas Gerais. Secretaria de Estado de Saúde de Minas Gerais (SESMG). Componentes Básico e Estratégico da Assistência Farmacêutica. 2ª ed. Belo Horizonte: SESMG; 2012.,³²32. Brasil. Ministério da Saúde (MS). Relação Nacional de Medicamentos Essenciais: RENAME 2014. 9ª ed. rev. e atual. Brasília: MS; 2015.. Besides, almost two-thirds of medications were acquired by means of public pharmacies. Such a result indicates an important participation of SUS in the access to medications in Minas Gerais, during the period of investigation. A factor contributing for this was the implementation of Rede Farmácia de Minas, inserted in the State Program for Pharmaceutical Assistance Restructuring, as a strategy to amplify the access and rational use of medications in the SUS context³³33. Minas Gerais. Rede Farmácia de Minas. Plano Estadual de Estruturação da Rede de Assistência Farmacêutica: Uma estratégia para ampliar o acesso e o uso racional de medicamentos no SUS. [acessado 2016 Jul 19]. Disponível em: https://www.saude.mg.gov.br/images/documentos/02%20Farmacia_de_Minas_050608.pdf
https://www.saude.mg.gov.br/images/docum... .

Studies in patients with DM associating polypharmacy with its explicative variables have not been found. Only studies in elderly have investigated the number of utilized medications with their associated factors. In this context, it is possible to perceive that the population of this study presents characteristics like those of elderly population, with an average age of 61.3 years and more than 60% of the interviewed people declaring to be 60 years old or more. So, studies developed in elderly population have been utilized for comparison.

Respecting to age, as higher the age group of DM patients, higher the odds for a patient to be in polypharmacy, which is in accordance with results from other studies¹¹11. Carvalho MF, Romano-Lieber NS, Bergsten-Mendes G, Secoli SR, Ribeiro E, Lebrão ML, Duarte YA. Polypharmacy among the elderly in the city of São Paulo, Brazil - SABE Study. Rev Bras Epidemiol 2012; 15(4):817-827.,¹⁹19. Bauer S, Nauck MA. Polypharmacy in people with Type 1 and Type 2 diabetes is justified by current guidelines - a comprehensive assessment of drug prescriptions in patients needing inpatient treatment for diabetes-associated problems. Diabet Med 2014; 31(9):1078-1085.,³⁴34. Jyrkkä J, Enlund H, Korhonen MJ, Sulkava R, Hartikainen S. Patterns of druguse and factors associated with polypharmacy and excessive polypharmacy in elderly persons: results of the Kuopio 75+ study: a cross-sectional analysis. Drugs Aging 2009; 26(6):493-503.,³⁵35. Loyola Filho AI, Uchoa E, Lima-Costa MF. A population-based study on use of medication by the elderly in Greater Metropolitan Belo Horizonte, Minas Gerais, Brazil. Cad Saude Publica 2006; 22(12):2657-2667.. The patients’ average age was like that found in the studies of Araújo et al.²²22. Araújo MF, Santos Alves PJ, Veras VS, Araújo TM, Zanetti ML, Damasceno MM. Drug interactions in Brazilian type 2 diabetes patients. Int J Nurs Pract 2013; 19(4):423-430. and Bauer and Nauck¹⁹19. Bauer S, Nauck MA. Polypharmacy in people with Type 1 and Type 2 diabetes is justified by current guidelines - a comprehensive assessment of drug prescriptions in patients needing inpatient treatment for diabetes-associated problems. Diabet Med 2014; 31(9):1078-1085.in DM patients of Fortaleza, Brazil, and Bad Lauterberg im Harz, in Germany.

Another factor contributing to the increase in the number of medications is the higher number of comorbidities⁷7. American Diabetes Association (ADA). 10. Older Adults. Diabetes Care 2016; 39(Supl. 1):S81-S85.,²⁴24. Pereira LRL, Andrade RCG, Pereira JGC, Marchetti JM. Avaliação de prescrições de medicamentos para pacientes com Diabetes Melito atendidos por uma Unidade Básica de saúde. Rev. Ciênc. Farm. Básica Apl. 2005; 26(3):199-203.,³⁵35. Loyola Filho AI, Uchoa E, Lima-Costa MF. A population-based study on use of medication by the elderly in Greater Metropolitan Belo Horizonte, Minas Gerais, Brazil. Cad Saude Publica 2006; 22(12):2657-2667.,³⁶36. Gomes MB, Gianella D, Faria M, Tambascia M, Fonseca RM, Réa R, Macedo G, Modesto Filho J, Schmid H, Bittencourt AV, Cavalcanti S, Rassi N, Pedrosa H, Atala Dib S. Prevalence of Type 2 diabetic patients within the targets of care guidelines in daily clinical practice: a multi-center study in Brazil. Rev Diabet Stud 2006; 3(2):82-87.. At this point, the observation is that many individuals can not to obtain an adequate control of their health conditions. In the study of Gomes et al.³⁶36. Gomes MB, Gianella D, Faria M, Tambascia M, Fonseca RM, Réa R, Macedo G, Modesto Filho J, Schmid H, Bittencourt AV, Cavalcanti S, Rassi N, Pedrosa H, Atala Dib S. Prevalence of Type 2 diabetic patients within the targets of care guidelines in daily clinical practice: a multi-center study in Brazil. Rev Diabet Stud 2006; 3(2):82-87., developed in DM patients presenting also different comorbidities, less than 30% of patients achieved the target of blood pressure control, about 25% achieved the body mass index < 25 Kg/m², 21% achieved the control of LDL-Cholesterol level and 46% achieved the adequate control of glycated hemoglobin. The presence of a higher number of comorbidities, associated with an inadequate control of these health conditions, contributes a lot to the increase in the number of in-use medications.

To have consulted the physician four or more times during the last year is associated with polypharmacy in DM patients, which has also been observed in other studies with elderly patients³⁵35. Loyola Filho AI, Uchoa E, Lima-Costa MF. A population-based study on use of medication by the elderly in Greater Metropolitan Belo Horizonte, Minas Gerais, Brazil. Cad Saude Publica 2006; 22(12):2657-2667.,³⁶36. Gomes MB, Gianella D, Faria M, Tambascia M, Fonseca RM, Réa R, Macedo G, Modesto Filho J, Schmid H, Bittencourt AV, Cavalcanti S, Rassi N, Pedrosa H, Atala Dib S. Prevalence of Type 2 diabetic patients within the targets of care guidelines in daily clinical practice: a multi-center study in Brazil. Rev Diabet Stud 2006; 3(2):82-87.. Linjakumpu et al.³⁷37. Linjakumpu T, Hartikainen S, Klaukka T, Veijola J, Kivelä SL, Isoaho R. Use of medications and polypharmacy are increasing among the elderly. J Clin Epidemiol 2002; 55(8):809-817. have pointed out that the increase of utilization of health services by the most older people could be responsible for the higher use of medications. The importance of the continued medical education, the observance of clinical protocols and therapeutic guidelines, the quality of medical prescription and pharmaceutical orientation should be reinforced here, to contribute to a better use of the high number of in-use medications by the DM patients. This demonstrates the importance of a multidisciplinary care in health, which involves actions of health education, self-care, adherence to proposed measures, not pharmaceutical interventions, among other³⁷37. Linjakumpu T, Hartikainen S, Klaukka T, Veijola J, Kivelä SL, Isoaho R. Use of medications and polypharmacy are increasing among the elderly. J Clin Epidemiol 2002; 55(8):809-817.

38. Cardoso AF, Queirós P, Ribeiro CF. Therapeutic self‐care management interventions for individuals with diabetes melito: systematic review. Rev Port Saúde Pública 2015; 33(2):246-255.

39. Costa JA, Balga RS, Alfenas RC, Cotta RM. Health promotion and diabetes: discussing the adherence and motivation of diabetics that participate in health programs. Cien Saude Colet 2011; 16(3):2001-2009.-⁴⁰40. Torres HC, Souza ER, Lima MHM, Bodstein RC. Intervenção educativa para o autocuidado de indíviduos com diabetes melito. Acta paul. enferm. 2011; 24(4):514-519..

The average time of diagnosis above 10 years showed an association with polypharmacy. According to the Booklet of Basic Attention – Diabetes⁴¹41. Brasil. Ministério da Saúde (MS). Estratégias para o cuidado da pessoa com doença crônica: diabetes melito. Brasília: MS; 2013. (Cadernos de Atenção Básica, nº 36). and Lipska et al.⁴²42. Lipska KJ, Krumholz H, Soones T, Lee SJ. Polypharmacy in the Aging Patient: A Review of Glycemic Control in Older Adults With Type 2 Diabetes. JAMA 2016; 315(10):1034-1045., with the progressive increase of diagnosis time, it is possible to observe the appearance of microvascular and macrovascular complications in the patients, mainly when they are not informed about their disease, on occasion of the diagnosis. Besides, it is observed that in nine years, 75% of DM patients need to make use of more than one medication for their glycemic control. Both factors increase the number of in-use medications and favor the presence of polypharmacy⁴³43. Polonsky WH, Fisher L, Schikman CH, Hinnen DA, Parkin CG, Jelsovsky Z, Petersen B, Schweitzer M, Wagner RS. Structured self-monitoring of blood glucose significantly reduces A1C levels in poorly controlled, noninsulin-treated type 2 diabetes: results from the Structured Testing Program study. Diabetes Care 2011; 34(2):262-267..

The bad or very bad health self-perception showed association with polypharmacy, an aspect observed also in other studies¹¹11. Carvalho MF, Romano-Lieber NS, Bergsten-Mendes G, Secoli SR, Ribeiro E, Lebrão ML, Duarte YA. Polypharmacy among the elderly in the city of São Paulo, Brazil - SABE Study. Rev Bras Epidemiol 2012; 15(4):817-827.,⁴⁴44. Santos TR, Lima DM, Nakatani AY, Pereira LV, Leal GS, Amaral RG. Medicine use by the elderly in Goiania, Midwestern Brazil. Rev Saude Publica 2013; 47(1):94-103.. According to Santos et al.⁴⁴44. Santos TR, Lima DM, Nakatani AY, Pereira LV, Leal GS, Amaral RG. Medicine use by the elderly in Goiania, Midwestern Brazil. Rev Saude Publica 2013; 47(1):94-103., the patients presenting a worst health self-perception, when using several medications, are searching for a solution to their health problems. In a study developed in Canada, a higher report of bad or very bad health self-perception has been observed respecting to observed in our study, associated mainly to the presence of depression and deficiencies associated or resulting from DM, besides the presence of other chronic comorbidities⁴⁵45. Badawi G, Gariépy G, Pagé V, Schmitz N. Indicators of self-rated health in the Canadian population with diabetes. Diabet Med 2012; 29(8):1021-1028..

The absence of regular physical activity and the cessation of normal activities are factors associated with polypharmacy in type 2 DM patients. According to the Brazilian Society of Diabetes (2015), the physical activity, associated with a food plan, could be beneficial to help in the glycemic control, in the weight loss, and in the increase of muscle mass, which should collaborate for the reduction of insulin resistance and better disease control²2. Sociedade Brasileira de Diabetes. Diretrizes da Sociedade Brasileira de Diabetes. 2014-2015. São Paulo: AC Farmacêutica; 2015.. Besides, Silva et al.⁴⁶46. Silva AL, Ribeiro AQ, Klein CH, Acurcio FA. Use of medications by elderly Brazilians according to age: a postal survey. Cad Saude Publica 2012; 28(6):1033-1045. have reported that the interruption of normal activities is related to the use of a larger number of medications.

It was observed that the availability of a health plan was associated with polypharmacy, as reported by other studies¹¹11. Carvalho MF, Romano-Lieber NS, Bergsten-Mendes G, Secoli SR, Ribeiro E, Lebrão ML, Duarte YA. Polypharmacy among the elderly in the city of São Paulo, Brazil - SABE Study. Rev Bras Epidemiol 2012; 15(4):817-827.,⁴⁶46. Silva AL, Ribeiro AQ, Klein CH, Acurcio FA. Use of medications by elderly Brazilians according to age: a postal survey. Cad Saude Publica 2012; 28(6):1033-1045.. According to Duarte (2012), people having a health plan possess higher income and more easy access to healthcare professionals and medications available in the market⁴⁷47. Duarte LR, Gianini RJ, Ferreira LR, Camargo MAS, Galhardo SD. Hábitos de consumo de medicamentos entre idosos usuários do SUS e de plano de saúde. Cad Saúde Colet 2012; 20(1):64-71.. In a study developed with DM patients linked to Medicare, in the United States, it has been observed that a half of the individuals with inadequate glycemic control had not their treatment intensified along five years, which could lead to DM complications and contributes for the polypharmacy increase⁴⁸48. Ajmera M, Raval A, Zhou S, Wei W, Bhattacharya R, Pan C, Sambamoorthi U. A Real-World Observational Study of Time to Treatment Intensification Among Elderly Patients with Inadequately Controlled Type 2 Diabetes Melito. J Manag Care Spec Pharm 2015; 21(12):1184-1193..

The limitations of this study are related to utilization of a reminder period of 15 days for the evaluation of medications use, which could generate a recall bias. We tried, however, to minimize such bias by means of the confirmation of use through the presentation of used products packages and respective prescriptions. Besides, the transversal method does not allow the establishment of cause-effect relationships. The data collection was executed in work schedules of people, from 08:00 am to 06:00 pm, which could have contributed for the selection of an older sample, composed by people inactive in terms of work. It is suggested that new studies should evaluate the possible benefits and harms of polypharmacy, of medication association and the influence of these conditions in the quality of life of DM patients, with the purpose to achieve a better use of medications and optimize the healthcare provided to these patients.

The polypharmacy presents a relevant prevalence among DM patients in Minas Gerais. Most of the interviewed people were using polypharmacy, which increases the risk for adverse reactions, cumulative toxicity, and drug interactions. This present study has brought deeper knowledge about the factors related to polypharmacy and it is expected that such information could contribute for the optimization of healthcare provided to patients with such a health condition, reinforcing the necessity of educational actions in health and the search for a better use of medications. Factors such as population aging, the increase of comorbidities, and the access to healthcare services contribute to increasing the number of medications utilized by the DM population. Because of that, there is the necessity to become available a sufficient number of enabled professionals to provide the adequate healthcare, improve the quality of medications use, and minimize the negative consequences in the health of this population.

Acknowledgments

The authors are grateful to the National Council of Scientific and Technological Development (in Portuguese: Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq), the Foundation for Investigation Support of Minas Gerais (Fundação de Amparo a Pesquisa de Minas Gerais - FAPEMIG), the UFMG Group for Investigation in Pharmacoepidemiology (Grupo de Pesquisas em Farmacoepidemiologia da UFMG), and the State Department of Health of Minas Gerais (Secretaria de Estado da Saúde de Minas Gerais) for their continuous support for this study.

The authors declare to be free of conflicts of interest.

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