Study under review: Reduction in Glycated Hemoglobin and Daily Insulin Dose Alongside Circadian Clock Upregulation in Patients With Type 2 Diabetes Consuming a Three-Meal Diet: A Randomized Clinical Trial.
Circadian rhythms are oscillatory, cyclical patterns in metabolism and metabolic molecules, like hormones, that occur over the course of a day. Over the last few years, accumulating evidence has pointed to the importance of circadian rhythms for health and metabolism. In particular, the processes involved in glucose metabolism display a circadian variation, meaning they function differently at different times of day. Under sedentary conditions, glucose tolerance and insulin sensitivity are higher in the morning compared to the evening in healthy people, and thus the elevation in blood glucose in response to the same meal is higher in the evening than in the morning. The change in blood glucose levels depending on meal timing in healthy people is shown in Figure 1. However, this variation during the day appears to be opposite in people with type 2 diabetes. Glucose tolerance increases during the day when using a glucose and insulin infusion, which might not represent a physiological scenario. Thus, different meal timing strategies might have distinct effects in participants with type 2 diabetes.
Trials involving people with diabetes that examine only meal timing are scarce and contradictory. One study has shown that consuming all calories in two versus six meals results in better improvements in bodyweight and glycemic parameters. However, another study found better glycemic management with six smaller meals when participants were eating under caloric balance. On the other hand, the distribution of energy among meals might also influence the results of meal timing interventions. For example, a bigger breakfast and small dinner appears to improve measures of glycemic dysregulation, compared to a smaller breakfast and bigger dinner.
Therefore, the authors of this study wanted to determine the effects of consuming a hypocaloric diet in three meals, with an energy and carbohydrate rich breakfast and low energy and low carbohydrate dinner, compared to consuming the same amount of calories spread throughout the day in six meals, on total daily insulin dose, bodyweight, glycemic control, and circadian clock gene expression.
In healthy participants, glucose tolerance and insulin sensitivity appear to follow a circadian fashion, measuring higher in the morning and decreasing during the day. Some studies suggest better glycemic control in participants with type 2 diabetes is derived from a lower meal frequency and more energy consumed during the early part of the day. Therefore, the authors of this study wanted to evaluate the effects of consuming three meals per day with a big breakfast on total daily insulin dose, bodyweight, glycemic control, and circadian clock gene expression compared to eating the same amount of calories in six meals.
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