ReFLeCT, a multicenter, prospective, observational study evaluated the safety and effectiveness of switching from other basal insulins to insulin degludec (degludec) in patients with type 1 (T1D) or type 2 diabetes (T2D) in routine clinical practice. ReFLeCT comprised a 4-week baseline period (pre-switch basal insulin) and 12-month follow-up period (degludec). The primary endpoint of overall hypoglycemia reported in patient diaries was reduced during the 12-month follow-up period vs baseline, without compromising glycemic control. In pre-specified subgroup analyses of the primary endpoint, we assessed if the overall result was robust in different subgroups, characterized according to baseline A1C (<7.5, ≥7.5–<8.5, ≥8.5–<9.5, ≥9.5%), diabetes duration (quartiles) and physician’s reason for initiating degludec (hypoglycemia [Yes/No]). The estimated rate ratios of hypoglycemia were similar within subgroups (no significant interactions), and demonstrated overall lower rates (the majority significantly lower) during the 12-month follow-up periods vs baseline in patients with T1D or T2D (Figure). Irrespective of baseline characteristics or physician’s reason for initiating degludec, switching to degludec from other basal insulins reduced rates of overall hypoglycemia in patients with T1D or T2D, in routine clinical practice.