Timing really matters when checking blood sugar levels. That is because each time point reveals something different about how the body processes glucose. “Fasting blood sugar is usually measured first thing in the morning, after at least 8 hours of no food or drink (except water). This gives us a baseline reading and is one of the most common and reliable ways to screen for diabetes. A fasting level between 100–125 mg/dL suggests prediabetes, while 126 mg/dL or higher on two occasions confirms diabetes,” said Dr Snehal Tanna, consultant diabetologist, Jupiter Hospital, Thane.
Post-prandial (after-meal) sugar, typically checked two hours after starting a meal, indicates how well the body handles sugar from food consumed. “This is especially helpful in detecting early blood sugar issues or assessing how effectively someone is managing their diabetes. A reading below 140 mg/dL is considered normal two hours after eating,” added Dr Tanna.
Random blood sugar can be tested at any time of the day, regardless of meals. “While less precise for diagnosis, a level of 200 mg/dL or more, especially if accompanied by symptoms like frequent urination or excessive thirst, can indicate diabetes,” Dr Tanna explained.
Each type of test serves a specific purpose: fasting sugar for diagnosis and routine monitoring, post-meal sugar to check how the body responds to food, and random sugar for urgent or symptomatic cases. “For best results, always follow test preparation instructions: fast properly, avoid physical activity before testing, and don’t smoke or consume caffeine. Also, some medications can affect readings, so it’s important to discuss your routine with the doctor beforehand,” advised Dr Tanna.
For individuals with diabetes, additional testing times provide more insight, said Dr Hiran S Reddy, consultant physician, diabetologist and critical care specialist, Gleneagles Hospital, Lakdi Ka Pul, Hyderabad.
Before meals (preprandial) helps determine how well blood sugar is controlled throughout the day.
Two hours after a meal (postprandial) shows how the body handles glucose spikes after eating.
Bedtime checks help monitor overnight glucose stability, especially in insulin-dependent diabetics.
For individuals with diabetes, additional testing times provide more insight (Photo: Getty Images/Thinkstock)
Another valuable tool is the HbA1c test, which gives a three-month average of blood glucose levels, but this is done in a lab setting, said Dr Reddy.
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So, “no single time is best for everyone,” as it depends on the purpose. “But when timed and interpreted correctly, these tests together give a complete picture of your glucose health,” said Dr Tanna.
Concurred Dr Reddy and shared that fasting blood sugar is ideal for screening, while multiple-time-point checks are better for those actively managing diabetes. “Consistency in timing and method is essential for accurate tracking, and all readings should be interpreted in consultation with a healthcare provider,” said Dr Reddy.
DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.