Will a 13-Hour Fast Affect Your Blood Sugar Reading?
Published on: June 26, 2026, 3:07 p.m. | Source: The Indian Express
Fasting for 13 hours instead of the recommended 8–12 hours is unlikely to significantly affect most blood sugar test results, but it can cause slight variations. According to diabetologist Dr Vijay Negalur, prolonged fasting may prompt the liver to release stored glucose into the bloodstream to maintain energy levels, which can sometimes lead to marginally higher blood sugar readings. However, for most people—especially those without diabetes—the difference is usually minimal. Factors such as age, medications, stress, sleep, physical activity, and overall metabolic health also influence results. While a 13-hour fast can still provide useful clinical information, doctors may interpret borderline results cautiously and recommend repeating the test under standard fasting conditions. The key is to follow the same fasting duration for future tests to ensure accurate comparisons over time.
