Intermittent fasting ameliorates PM exposure-induced abnormalities in glycaemic control.

Exposure to ambient fine particulate matter (PM) elicits various abnormalities in glycaemic control and thus correlates with type 2 diabetes. Intermittent fasting is an emerging treatment for type 2 diabetes. This study, therefore, tested whether intermittent fasting ameliorates PM exposure-induced abnormalities in glycaemic control. To this end, C57Bl/6 J mice were exposed to filtered air (FA) or concentrated ambient PM (CAP) for 16 weeks and concurrently subject to ad libitum feeding or intermittent fasting. The food intake assessment showed that CAP exposure transiently reduced food intake in ad libitum fed mice, but persistently reduced food intake in intermittently fasted mice. In contrast, CAP exposure persistently promoted mouse weight gain in ad libitum fed mice, while intermittent fasting blocked this CAP exposure-induced weight gain. The glucose homeostasis assessments revealed that CAP exposure elicited insulin resistance and glucose intolerance and meanwhile increased glucose-induced insulin secretion (GIIS). The insulin resistance and glucose intolerance, but not the increase in GIIS, induced by CAP exposure were blocked by intermittent fasting. Analysis of Akt phosphorylation, the indicator of local insulin signaling, showed that CAP exposure reduced insulin signaling in the liver and adipose tissues but not in the skeletal muscle. Intermittent fasting blocked CAP exposure-induced insulin resistance in the liver but not in the adipose tissues. The present study demonstrates that intermittent fasting ameliorates PM exposure-induced insulin resistance and glucose intolerance, strongly supporting that it may be used to prevent type 2 diabetes due to exposure to PM.