Multimorbidity, Polypharmacy, Severe Hypoglycemia, and Glycemic Control in Patients Using Glucose-Lowering Drugs for Type 2 Diabetes: A Retrospective Cohort Study Using Health Insurance Claims in Japan

IntroductionThis study aimed to understand the actual status of multimorbidity and polypharmacy among patients with type 2 diabetes using glucose-lowering drugs, and to assess the effects of patient characteristics on severe hypoglycemia and glycemic control.MethodsWe designed a retrospective cohort study using health insurance claims and medical checkup data in Japan from April 2016 to February 2021 and identified patients with type 2 diabetes who were prescribed glucose-lowering drugs. We analyzed data on patient characteristics, including multimorbidity and polypharmacy, calculated the incidence rate for severe hypoglycemic events, applied a negative binomial regression model to explore factors that affected severe hypoglycemia, and analyzed the status of glycemic control in the subcohort for which HbA1c data were available.ResultsWithin the analysis population (n = 93,801), multimorbidity was present in 85.5% and mean +/- standard deviation for oral drug prescriptions was 5.6 +/- 3.5 per patient, while for those aged 75 years or older these numbers increased to 96.3% and 7.1 +/- 3.5, respectively. The crude incidence rate for severe hypoglycemia was 5.85 (95% confidence interval 5.37, 6.37) per 1000 person-years. Risk factors for severe hypoglycemia included younger and older age, prior severe hypoglycemia, use of insulin, sulfonylurea, two-drug therapy including sulfonylurea or glinides, three-or-more-drug therapy, excessive polypharmacy, and comorbidities including end-stage renal disease (ESRD) requiring dialysis. Subcohort analysis (n = 26,746) showed that glycemic control is not always maintained according to guidelines.ConclusionPatients with type 2 diabetes, particularly older patients, experienced high multimorbidity and polypharmacy. Several risk factors for severe hypoglycemia were identified, most notably younger age, ESRD, history of severe hypoglycemia, and insulin therapy.