Diurnal Rhythm of Insulin Sensitivity in Subjects with Normal and Impaired Glucose Tolerance¹)

Abstract

We studied the insulin sensitivity in 5 normal subjects and 5 subjects with impaired carbohydrate tolerance using the glucose controlled insulin infusion system (BIOSTATOR). During a fixed glucose infusion rate of 2 mg/kg b.w./min, the computer program was set to maintain the plasma glucose concentration at 4.44 mmol/l. The ratio of infused exogenous insulin to infused glucose served as a measure of insulin sensitivity. Calculating the average insulin glucose ratio for 24 hours, the mean values amounted to 3531 and 9319 ng/gm (p less than 0.01) in subjects with normal and impaired carbohydrate tolerance, respectively, indicating that insulin resistance is the main cause of decreased glucose utilization in the latter group. Circadian rhythms of insulin sensitivity occur in both groups in a similar fashion. The insulin sensitivity was higher in the afternoon (1200-1800) as compared to the night. Thus, diurnal variations in insulin sensitivity are independent of disturbances of glucose metabolism.

The effect of rising vs. falling glucose level on amperometric glucose sensor lag and accuracy in Type 1 diabetes

“…After the first meal of the day (but not the second), high glycaemic index meals resulted in much higher postprandial glucose levels vs. low glycaemic index. Several investigators have commented on such differences between meals and have used terms such as the 'breakfast effect' or 'second meal phenomenon' to describe this effect [16][17][18], which might be attributable to continued presence of the pre-breakfast insulin bolus or a diurnal change in insulin sensitivity or other metabolic factor [19,20]. In our study, the change in glucose after meals was easily detectable using the sensor.…”

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

“…In one trial employing a frequently-sampled intravenous glucose tolerance test in normal-weight participants, insulin sensitivity was impaired by 34% in the evening relative to the morning [50]. Impairments in insulin sensitivity later in the day have also been confirmed using insulin tolerance tests [46, 68, 69], mixed meal tolerance tests using the triple tracer technique [55], constant glucose infusion procedures using isotope tracers [70], and a 24-hour glucose-controlled insulin infusion procedure reminiscent of a clamp [71]. The diurnal rhythm in peripheral insulin sensitivity is likely due to both core intracellular pathways mediating glucose uptake and circulating factors.…”

Influence of dioxin on the daily variation of insulin sensitivity in mice

“…Insulin sensitivity exhibits a daily variation with the higher value at day-time compared to that at night-time in human subjects (Schulz et al, 1983). Insulin sensitivity is also reported to be higher during an active period than during an inactive period in nocturnal rodents (la Fleur et al, 2001).…”