Breakfast glycaemic response in patients with type 2 diabetes: Effects of bedtime dietary carbohydrates

Objectives: Bedtime carbohydrate (CHO) intake in patients with type-2 diabe tes may improve glucose tolerance at breakfast the next morning. We examine d the 'overnight second-meal effect' of bedtime supplements containing 'rap id' or 'slow' CHOs. Design: Randomized cross-over study with three test-periods, each consistin g of two days on a standardized diet, followed by a breakfast tolerance tes t on the third morning. Setting: The Lundberg Laboratory for Diabetes Research, Sahlgrenska Univers ity Hospital, Goteborg, Sweden. Subjects: Sixteen patients with type 2 diabetes on oral agents and/or diet. Interventions: Two different bedtime (22.00 h) CHO supplements (0.46 g avai lable CHO/kg body weight) were compared to a starch-free placebo ('normal' food regimen). The CHOs were provided as uncooked cornstarch (slow-release CHOs) or white bread (rapid CHOs). Results: On the mornings after different bedtime meals we found similar fas ting glucose, insulin, free fatty acid and lactate levels. However, the gly caemic response after breakfast was 21% less after uncooked cornstarch comp ared to placebo ingestion at bedtime (406 +/- 46 vs 51 +/- 61 mmol min l(-1 ), P < 0.01). In contrast, it did not differ when the evening meal consiste d of white bread (451 +/- 57 mmol min l(-1)) compared to placebo. According to an in vitro analysis, uncooked cornstarch contained similar to 4 times moro slowly digestible starch as compared to white bread. Conclusions: A bedtime meal providing uncooked cornstarch improved breakfas t tolerance the next morning while, in contrast, this nas not found followi ng a bedtime meat of white bread. The results are consistent, therefore, wi th the concept that an increased intake of slowly digestible carbohydrates exert an overnight second-meal effect in patients with type 2 diabetes.