10.3389/fendo.2019.00554.s001 Paul de Goede Paul de Goede Ewout Foppen Ewout Foppen Wayne I. G. R. Ritsema Wayne I. G. R. Ritsema Nikita L. Korpel Nikita L. Korpel Chun-Xia Yi Chun-Xia Yi Andries Kalsbeek Andries Kalsbeek Image_1_Time-Restricted Feeding Improves Glucose Tolerance in Rats, but Only When in Line With the Circadian Timing System.TIF Frontiers 2019 feeding behavior metabolism intravenous glucose tolerance test (ivGTT) insulin sensitivity shift-work Type 2 diabetes mellitus (T2DM) 2019-08-21 09:25:52 Figure https://frontiersin.figshare.com/articles/figure/Image_1_Time-Restricted_Feeding_Improves_Glucose_Tolerance_in_Rats_but_Only_When_in_Line_With_the_Circadian_Timing_System_TIF/9699104 <p>Epidemiological studies indicate that shift-workers have an increased risk of type 2 diabetes mellitus (T2DM). Glucose tolerance and insulin sensitivity both are dependent on the circadian timing system (i.e., the time-of-day) and fasting duration, in rodents as well as humans. Therefore, question is whether manipulation of the circadian timing system, for example by changing the timing of feeding and fasting, is a potential preventive treatment for T2DM. Time-restricted feeding (TRF) is well-known to have profound effects on various metabolic measures, including glucose metabolism. However, experiments that directly measure the effects of TRF on glucose tolerance and/or insulin sensitivity at different time points throughout the 24 h cycle are lacking. Here we show, in rats, that TRF in line with the circadian timing system (i.e., feeding during the active phase) improves glucose tolerance during intravenous glucose tolerance tests (ivGTT) in the active phase, as lower insulin levels were observed with similar levels of glucose clearance. However, this was not the case during the inactive phase in which more insulin was released but only a slightly faster glucose clearance was observed. Contrasting, TRF out of sync with the circadian timing system (i.e., feeding during the inactive phase) worsened glucose tolerance, although only marginally, likely because of adaptation to the 4 week TRF regimen. Our results show that TRF can improve glucose metabolism, but strict adherence to the time-restricted feeding period is necessary, as outside the regular eating hours glucose tolerance is worsened.</p>