Background Diabetes among older people is becoming more common worldwide. Polypharmacy is an important issue among older people with multimorbidity; however, relevant studies focusing on older people with diabetes are scarce. Therefore, the role of polypharmacy in this vulnerable population remains uncertain. The aim of this study is to investigate the prevalence of polypharmacy among older people with and without diabetes, and to determine the potential risk factors for polypharmacy.

Methods A nationally representative cross-sectional study, ELSA 2012/2013, was used and 7729 participants aged 50–109 were investigated. Polypharmacy was defined as taking five to nine long-term used medications daily for chronic diseases or chronic symptoms, while using ten or more medications was categorised as excessive polypharmacy. The presence of illness was defined as either self-reported diagnosis or being prescribed specific medications for the condition. The number of comorbidities was generated based on the combined diagnoses excluding diabetes. Multinomial logistic regression was applied to estimate risk factors for polypharmacy, and potential social determinants were also included.

Results The prevalence of polypharmacy was 21.4% in 2012, and only 3% was excessive polypharmacy. 51.6% of people with type 2 diabetes reported polypharmacy and 10.2% excessive polypharmacy. These rates were significantly higher than the 16.4% polypharmacy and 1.8% excessive polypharmacy among people without diabetes (p<0.001). 74.6% diabetic people had three or more comorbidities, compared with 40.8% in people without diabetes (p<0.001). Among people with three or more comorbidities, polypharmacy was present in 61.5% of people with diabetes, compared with 36.0% in people without diabetes. Significant risk factors for polypharmacy were diabetes (Relative-risk ratios/RRR=4.06, 95% CI 3.38, 4.86), older age (RRR=1.02, 95% CI 1.01, 1.03), male (RRR=0.64, 95% CI 0.55, 0.75), more comorbidity (RRR=2.46, 95% CI 2.30, 2.62), living with a partner (RRR=1.20, 95% CI 1.01, 1.42), and less wealth (RRR=0.93, 95% CI 0.87, 0.98). However, age, living with partner, and wealth were not significantly related to excessive polypharmacy. Diabetes and the number of comorbidities were predominant risk factors for excessive polypharmacy.

Conclusion Polypharmacy was a prevalent phenomenon in the English older population, and it was more severe in people with diabetes. The presence of diabetes and having comorbidities were the main contributors to polypharmacy and excessive polypharmacy after adjusting for important covariates. Current evidences confirm both health condition and socioeconomic status are associated with medication use. This research is currently ongoing, and more factors will be studied in the future.