An age-stratified cross-sectional study of antidiabetic and non-antidiabetic drugs prescribed to Japanese outpatients with diabetes.

Polypharmacy, common in patients with diabetes, may cause adverse drug reactions. The number of antidiabetic and non-antidiabetic drugs prescribed to patients in different age groups remains unclear. The aim of this study was to examine the number and class of antidiabetics and non-antidiabetics prescribed to Japanese patients with diabetes, stratified by age for reducing polypharmacy. This cross-sectional study examined all prescriptions of patients prescribed antidiabetics at 257 pharmacies of Matsumotokiyoshi Holdings in Japan from May 2018 to March 2019. Total prescription numbers including antidiabetic drugs were 263,915 in this study. Mean numbers of antidiabetic drugs per prescription were 1.71, 2.17, and 1.52 in the patient age groups of 10-19, 50-59, and 90-99 years, respectively. Count of antidiabetics was not related to age. However, the mean total number of drugs prescribed increased with age, which was 2.22 and 7.99 in the age groups of 10-19 and 90-99 years, respectively. The linear regression coefficient (b) according to age was 0.07 (p < 0.001) for 10-99 years. The mean non-antidiabetic number of agents prescribed increased with age among 10-99 years (b = 0.07, p < 0.001). Among outpatients treated for diabetes, dipeptidyl peptidase-4 inhibitors (29%) and antihypertensive, β-blocking and renin-angiotensin system blocking drugs (32%) were the most prescribed antidiabetics and non-antidiabetics in all ages, respectively. The number of prescribed antidiabetic agents did not increase with age, whereas the total and non-antidiabetic numbers of medications prescribed increased linearly. For reduction of polypharmacy in older people with diabetes, we need to focus on non-antidiabetics.