Effect of carbohydrate restriction in the first meal after an overnight fast on glycemic control in people with type 2 diabetes: a randomized trial.

People with type 2 diabetes are advised to consume an even meal distribution of carbohydrate. Whether this distribution is optimal is unknown.

Our objective was to show that omitting carbohydrate in the first meal after a fast would lead to an augmented lunch response.

Two diets of 1-d duration that differed only in the breakfast-meal composition (carbohydrate or no carbohydrate) were consumed on sequential days in a randomized crossover study. The procedure was repeated in the alternate order 1 wk later. Blood glucose concentrations were tested with the use of continuous glucose monitoring. The primary endpoints were the percentage of time spent with a blood glucose concentration >10 mmol/L (%T >10) and peak blood glucose (Gmax). The following 45 adults with type 2 diabetes were recruited: subjects with glycated hemoglobin (HbA1c) ≤7% and subjects with HbA1c ≥8%. Twenty-eight adults completed the study.

The daily Gmax was significantly lower after the no-carbohydrate breakfast than after the carbohydrate breakfast (11.0 ± 0.4 and 12.1 ± 0.4 mmol/L, respectively; P = 0.003) whereas the %T >10 throughout the day was a nonsignificant 22% less after the no-carbohydrate breakfast than after the carbohydrate breakfast (13% ± 10% compared with 10% ± 8%; P = 0.09). Gmax over 5 h after breakfast was significantly lower after the no-carbohydrate meal (by 1.9 ± 0.4 mmol/L; P < 0.001), and the %T >10 was lower after the no-carbohydrate meal than after the carbohydrate meal (11% ± 3% compared with 26% ± 4%, respectively; P < 0.001).

The withholding of carbohydrate in the first meal results in significantly decreased Gmax after the meal, but the lunch response is not affected. Overall daily control is not significantly improved. This trial was registered at the Australian New Zealand Clinical Trials Registry as ACTRN12609000331235.