Objective To evaluate the impact of different protein composition of bedtime snack on prevention of nocturnal hypoglycemia in older patients with type 2 diabetes mellitus, and to provide reference for glucose management in this population.Methods Three hundred older patients were randomized to one of two groups, with 150 in each.Their glucose level at bedtime (22:00) was measured using a continuous glucose monitoring system and if it was between 4.0 and 5.6 mmol/L, 9 g of low-protein biscuits （containing 1.3 g protein） were given for the control group, while high-protein substitutions （20 g of milk powder dissolved in 100 mL of water containing 6.6 g protein） were given for the intervention group.The incidence of nocturnal hypoglycemia and the next-day glucose levels were compared between the two groups.Results The incidence of nocturnal hypoglycemia was 3.75% in the intervention group and 12.50% in the control group, showing significant difference （P＜0.05）.The mean amplitude of glycemic excursion, time in range, time below range, as well as the rates of these parameters during the target range were significantly better in the intervention group compared with the control group （all P＜0.05）.Conclusion Consuming a high protein bedtime snack can effectively reduce the incidence of nocturnal hypoglycemia in older patients with type 2 diabetes and improve next-day glycemic control.