Table 2.

Metabolic effect of circadian genes.

Gene	Activity
IL-6	•Activates AMPK •Stimulates glucagon-like peptide 1 (GLP-1) secretion from intestinal L cells and pancreatic α cells
Nrf-2	•Activation of PPAR-δ. •Increase glucose flux through the pentose phosphate pathway. •Increase glycolysis •Inhibition of fat synthesis by sequestering NADPH •Increase oxidation of fatty acid and glucose. •Increase in glucose metabolism
CRY 1/2	•Activated in morning exercise but not activated in evening exercise. •Degradation of PPAR-δ
PPAR- δ	•Increase glucose and fatty acid metabolism •Suppress hepatic glucose output. •Increase glucose flux through the pentose phosphate pathway. •Enhance glucose stimulated insulin secretion (GSIS)
AMPK	•Higher levels of AMPK lead to the degradation of CRY1/2 leading to increased PPAR- δ activity.

Abbreviation: IL-6 ​= ​interleukin-6, Nrf-2 ​= ​Nuclear factor E2 related factor-2, CRY1/2 ​= ​Cryptochrome 1and 2, PPAR-δ ​= ​Peroxisome proliferator-activated receptors-δ, AMPK ​= ​AMP-activated protein kinase.