Hip and vertebral fracture risk after initiating antidiabetic drugs in Japanese elderly: a nationwide study

Introduction We aimed to clarify the risks of initiating antidiabetic drugs for fractures using a nationwide health insurance claims database (NDBJ). Materials and Methods Patients aged ≥ 65 years initiating antidiabetic drugs at the outpatient department were enrolled after a 180-day period without prescribed antidiabetic drugs and followed with during 2012–2018 using NDBJ. The adjusted hazard risks (HRs) of each antidiabetic drug (thiazolidine, alpha-glucosidase inhibitor, dipeptidyl peptidase-4 [DPP-4] inhibitor, sulfonylurea, glinide, and insulin) for fractures compared with biguanide were obtained adjusting for age, gender, polypharmacy, dementia, and the other antidiabetic drugs. Results The DPP-4 inhibitor was the most often prescribed antidiabetic drug followed by biguanide with prescribed proportions of 71.7% and 12.9%. A total of 4,304 hip fractures and 9,388 vertebral fractures were identified among the 966,700 outpatient participants. Compared with biguanide, insulin, alpha-glucosidase inhibitor, and DPP-4 inhibitor were related to increased hip fracture risks. Vertebral fracture risk was higher in outpatients prescribed with insulin, thiazolidine, and DPP-4 inhibitor compared with biguanide. Patients prescribed insulin for hip and vertebral fractures’ adjusted HRs were 2.17 (95% CI 1.77–2.66) and 1.45 (95% CI 1.24–1.70), respectively. Those prescribed DPP-4 inhibitor for hip and vertebral fractures’ adjusted HRs were 1.27 (95% CI 1.15–1.40) and 1.20 (95% CI 1.12–1.28), respectively. Conclusions Initiating insulin increased the risk of not only hip fractures but also vertebral fractures. Patients initiating antidiabetic drugs had increased risks of hip and vertebral fractures compared with those initiating biguanide independently for age, gender, polypharmacy, and dementia in the Japanese elderly.