Effect Meal Timing in Type 2 Diabetes on Serum Induced SIRT1 and Clock Gene Expression in Hepatocytes

The timing of many physiological processes, including glucose metabolism, is coordinated by the circadian clock gene system. The circadian clock regulation, optimize glucose metabolism for the consumption of high energy and carbohydrate (CH) meals in the early hours of the day and for fasting at evening and night. Circadian disruption which occurs when the meal timing is not aligned with the circadian clock rhythms like skipping breakfast, overeating CH at night or eating CH all day, lead to desynchronized clock genes and can result in adverse health outcomes like insulin resistance, obesity hyperglycemia and T2D. Although the clock genes are disseminated in almost all peripheral tissues, those localized in the liver, are particularly important for the regulation of glucose metabolism, influencing the enzymatic determinants of the hepatic glucose output, by enhancing glycogen storage and suppressing nocturnal hepatic glucose production (glycogenolysis and gluconeogenesis sequentially).Therefore, the disruption of the hepatic clock genes lead to fasting, nocturnal, and to postprandial hyperglycemia in T2D. The researchers had previously shown in T2D, that compared to 6Mdiet, the 3Meal diet timing schedule, was most effective in reducing body weight, HbA1c, overall hyperglycemia, and led to up-regulation of SIRT1 and Clock Genes mRNA expression in leukocytes. However, this effect of meal timing had never been explored in liver cells. The investigators hypothesized that compared to Allday Diet (6Mdiet), the serum collected from T2D participants following Breakfast Diet (3Mdiet) will up-regulate SIRT1 and Clock Genes oscillatory mRNA expression in cultured hepatocytes.