Relationship between the early initiation of insulin treatment and diabetic complications in patients newly diagnosed with type 2 diabetes mellitus in Korea: a nationwide cohort study.

Aims To evaluate the relationship between early insulin initiation within a year after type 2 diabetes mellitus (T2DM) diagnosis and the risk of diabetic complications. Materials and methods We conducted a cohort study using the Korean National Health Insurance Service database. The study subjects were newly diagnosed with T2DM between 2009 and 2013. After applying a propensity score matching (1:1) to the cohort of patients who received ≥2 oral antidiabetic drugs (OADs) or insulin as the first prescription within one year after T2DM diagnosis, we computed hazard ratios (HRs) and 95% confidence intervals (CIs) using a Cox proportional hazards regression to compare the risk of diabetes-related microvascular and macrovascular complications and all-cause mortality in insulin versus OAD initiators. Results Within the cohort, 52,188 and 1,804 patients received OAD and insulin, respectively. After matching, each group contained 534 patients. Compared with the OAD group, the risk of overall microvascular complications was significantly higher in insulin (HR=1.48; 95% CI=1.28-1.71). No increased risks of overall macrovascular complications (HR=0.90; 95% CI=0.62-1.30) and all-cause mortality were observed (HR=1.06; 95% CI=0.67-1.68). Conclusions In our study, early insulin treatment was not associated with the risk of macrovascular complications and all-cause mortality compared to OAD treatment; however, the risk of microvascular complications was higher in the insulin group.