Circadian Rhythms of Carbohydrate Metabolism in Women with Different Types of Obesity

Abstract

Blood levels of glucose and immunoreactive insulin were assessed in women with android and gynoid types of obesity or normal body weight (control group) in the dynamics of oral glucose tolerance test in the morning and in the evening. In the control group, the mean concentrations of glucose and immunoreactive insulin were significantly higher in the evening at all test terms (0, 60 and 120 min), which is indicative of physiological insulin resistance in the evening. In the group of women with gynoid obesity, no difference in the levels of glucose and immunoreactive insulin was revealed in the morning and evening tests, but in the evening tests, glucose (60 and 120 min) and immunoreactive insulin (120 min) levels were lower than in the control group. In the group of women with android obesity, the evening glucose level on minutes 60 and 120 of the test was higher than in the morning, but immunoreactive insulin did not vary throughout the day and on minutes 60 and 120 it surpassed the corresponding parameter in the control group by 2-4 times. In case of gynoid obesity, glucose load was followed by hyperinsulinemia and hypoglycemia; in android obesity, it was followed by hyperinsulinemia, hyperglycemia, and insulin resistance irrespective of the time of the day.

Hormonal Regulation of Carbohydrate and Fat Metabolism in Women with Different Obesity Types in the Food Deprivation Test

“…Initial differences of carbohydrate metabolism in two groups, such as elevated levels of blood glucose and insulin in women with android obesity compared to those with gynoid obesity, are consistent with previously described characteristics of carbohydrate metabolism in women with different obesity types in response to glucose load in different phases of circadian rhythm (12). Glucose load in women with gynoid obesity was accompanied by functional hyperinsulinemia and postprandial hypoglycemia, whereas women with android obesity had absolute hyperinsulinemia, insulin resistance and hyperglycemia irrespective of the time of the day (12).The examination of women with android obesity also revealed typical disturbances of lipid metabolism manifested by initially elevated levels of LDL cholesterol and a reduced levels of HDL cholesterol, which is consistent with other authors' findings (13).…”

Circadian regulation of glucose, lipid, and energy metabolism in humans

“…The first evidence for circadian regulation of glucose metabolism emerged in the late 1960’s and 1970’s when several studies reported diurnal variations in glucose tolerance [33–47]. Since then, more than a dozen human studies have reported the existence of a diurnal rhythm in oral glucose tolerance, typically peaking in the morning, with impairments in glucose tolerance in the afternoon and evening [33–49]. Importantly, these time-of-day effects are independent of the fasting duration [40, 48].…”

“…Intriguingly, diurnal rhythms in glucose tolerance, insulin levels, and peripheral insulin sensitivity are attenuated, phase delayed, or absent in obese individuals [35, 39, 49, 50] and may be altered in aged individuals [39, 54]. Moreover, they are absent or inverted ( phase delayed by several hours) in adults with type 2 diabetes [34, 35, 47, 62, 80].…”

Combinatorial regulation of hepatic cytoplasmic signaling and nuclear transcriptional events by the OGT/REV-ERBα complex

“…In addition, AKT phosphorylation peaks at night in mouse liver when Rev-erb α expression is lowest ( 38 , 39 ). Insulin signaling follows a circadian rhythm in humans, with a low insulin responsiveness being observed in the evening when REV-ERBα is expressed ( 40 , 41 ). These data are in line with our observation that physiologically (ZT0) or genetically induced ( Rev-erb α −/− mice) REV-ERBα depletion reduces liver OGT protein content and favors AKT phosphorylation, hence leading to increased insulin responsiveness.…”