Previous studies have shown a considerable reduction in hyperglycemia after the second meal of the day, provided that breakfast had been taken. The preservation of this effect in Type 2 diabetes was not confirmed until recently. Postprandial hyperglycemia acts as an independent risk factor for cardiovascular disease, a major cause of death in subjects with Type 2 diabetes. It was hypothesized that post-breakfast hyperglycemia in subjects with Type 2 diabetes could be improved non-pharmacologically by using a high-protein, low-carbohydrate prebreakfast snack.
Researchers studied 10 men and women with diet- and/or metformin-controlled Type 2 diabetes. Metabolic changes after breakfast were compared between 2 days: breakfast taken only and soya-yogurt snack taken prior to breakfast.
The results showed that there was a significant lower rise in plasma glucose on the snack day. The incremental area under the glucose curve was 450 ± 55 mmol · min/l on the snack day compared with 699 ± 99 mmol · min/l on the control day (P = 0.013). The concentration of plasma free fatty acids immediately before breakfast correlated with the increment in plasma glucose (r = 0.50, P = 0.013).
This study demonstrated for the first time that the provision of a practical, high-protein, low-carbohydrate snack prior to breakfast reduced by 40% the postprandial plasma glucose increment in people with Type 2 diabetes. These findings confirm a potent expression of the second-meal effect in people with Type 2 diabetes. The importance of the present observation is that a more practical means of improving glucose tolerance could potentially be of therapeutic benefit in people with Type 2 diabetes.
Researchers observed no effect of the prior snack on insulin secretion after breakfast. The mechanism underlying the second-meal effect has been shown to be due to suppression of plasma FFA, allowing greater storage of glucose as muscle glycogen. They had previously demonstrated a strong negative correlation between the decrease of preprandial plasma FFA levels and the postmeal glucose increment. In the present study, a significant positive correlation was found between prebreakfast plasma FFA and the rise in postprandial plasma glucose concentration.
The snack used in the present study was empirically designed. It will be important to optimize both the composition of the snack and the interval before breakfast to maximize the benefit of this approach. In everyday life, the gap between snack and breakfast would have to be accommodated, for instance, by delaying breakfast until mid-morning. Although the snack induced a small increase in plasma glucose, it was minimal and unlikely to contribute to the hyperglycemic burden. The sample size was dictated by prior power calculation (80% power with 10 subjects).
The study demonstrated that a high-protein, low-carbohydrate snack before breakfast attenuates postbreakfast hyperglycemia and further studies must determine whether long-term use is associated with improvement in A1c.
Diabetes Care. 2010;33(12):2552-2554