We evaluated the efficacy and safety of switching to insulin degludec (IDeg) from insulin glargine (IGlar) as basal-bolus therapy in young people with type 1 diabetes. The subjects were 36 patients, 21.3±1.0 years of age, with type 1 diabetes. IGlar had previously been injected once daily in 25 patients and twice daily in 11. They were then switched from IGlar to once-daily injection of IDeg. Both fasting plasma glucose (FPG) and HbA1c levels decreased significantly from 134±3.9 mg/dL and 7.9±0.2% at baseline to 116±2.2 mg/dL and 7.4±0.2% at 12 months after starting IDeg (P<0.0001 and P≤0.001, respectively). Overall and nocturnal hypoglycemia (PG<70 mg/dL) frequencies also decreased significantly from 4.9±0.7 and 2.0±0.3 times/month to 2.4±0.3 and 0.4±0.1 times/month at 12 months after starting IDeg (P≤0.005 and P<0.0005, respectively). The daily basal insulin dose was significantly reduced from 0.48±0.04 units/kg/day at baseline to 0.38±0.03 units/kg/day at the end of the study period (P<0.0001), which corresponded to 79.2% of the baseline value. Trends were similar in patients receiving the once-daily injection and those given twice-daily injections, but basal-insulin value reductions from baseline were more marked in patients receiving twice-daily injections of basal insulin (76.0% vs. 82.6% of the baseline value). These results suggest that switching from IGlar to an appropriate dose of IDeg may effectively control hyperglycemia while reducing the frequency of hypoglycemia episodes in young Japanese people with type 1 diabetes.