CLOCK and Hyperglycemia: While PER1 influences blood glucose levels, blood glucose itself can regulate PER1 expression in tissues: hyperglycemia can disrupt the rhythmic expression of PER1 in the liver and olfactory bulb, leading to behavioral abnormalities (79), whereas glucose restriction induces the expression of the circadian clock gene PER1 via the AMP-activated protein kinase (AMPK) - SIRT1 pathway (80).