Fasting blood sugar can sometimes be higher after a 13-hour fast than after an 8-hour fast because the body actively works to maintain glucose levels even when no food is consumed. Endocrinologist Dr Sukirti Misra explains that hormones released in the early morning, such as cortisol and growth hormone, can trigger the liver to release stored glucose into the bloodstream—a phenomenon known as the "dawn phenomenon." Prolonged fasting can also prompt the liver to produce more glucose to supply ene