Effect of oral protein hydrolysate on glucose control in patients with gestational diabetes

In type 2 diabetic patients, a casein-based protein hydrolysate has been shown to increase plasma insulin and to lower plasma glucose. In the present study, we examined the acute and prolonged effects of protein hydrolysate on postprandial glucose, insulin and C-peptide responses after a standardised breakfast and the effect on daily glucose control in patients with gestational diabetes.

In a single-centre randomised double blind placebo controlled design, patients with mild gestational diabetes (no use of insulin or oral antidiabetic agents; n = 26/group) were allocated to receive a protein hydrolysate drink, 8.5 g before breakfast and 8.5 g before dinner or a placebo drink which was identical to the protein hydrolysate drink in appearance and taste, yet lacked carbohydrate, fat or protein, for 8 days.

Baseline characteristics including fasting levels of glucose, insulin, C-peptide and insulin-glucose ratio were similar between the groups. Compared to the placebo drink, neither the first dose of the protein hydrolysate drink nor the final dose had effects on 4-h area under the curve for plasma levels of insulin and C-peptide, or the insulin-to-glucose ratio; however, plasma glucose was moderately lower between t = 45, 60 and 75 min. In addition, mean daily capillary glucose levels were lower in the protein hydrolysate group. Two patients in the PH drink group had to be withdrawn because of vomiting after the first dose.

In patients with gestational diabetes, a twice-daily dose of 8.5 g of protein hydrolysate of casein had no insulinotropic effects, but did moderately reduce plasma glucose levels, suggesting an increase in insulin sensitivity.