The standard for measuring post-meal blood sugar is known as "two hours after eating." If it takes longer than usual to finish a meal, does the measurement time change? A reader asked about their concerns regarding post-meal blood sugar.

Meal times usually take about 30 to 40 minutes, but sometimes they last longer. When measuring post-meal blood sugar, do you start timing from the moment you take the first sip, or should you measure from the time you finish eating completely?

Q. When exactly should I measure post-meal blood sugar?

Measure at the second hour after the start of the meal

Post-meal blood sugar should be measured two hours after the 'first sip' time. Although it varies depending on the type and amount of food consumed and the body's glucose metabolism ability, generally, blood sugar peaks two hours after starting a meal, so it is measured at that time.

When glucose enters the bloodstream, insulin begins to be secreted at its peak from the pancreas. After that, for one or two hours, insulin continues to be secreted to lower the elevated blood sugar. After two hours, insulin secretion stops, and the blood insulin concentration decreases. In other words, all the processes of carbohydrate metabolism—digestion, absorption, blood sugar rise, and insulin secretion—occur within two hours after a meal.

Since the peak of blood sugar rise due to food intake occurs within two hours and then gradually decreases to near normal levels, measuring at the point when blood sugar is at its highest allows us to assess the body's blood sugar regulation ability.

In situations such as buffets or course meal restaurants where you dine for more than an hour, measure two hours after the start of food intake. Although the peak blood sugar level may vary depending on the amount of food consumed and the nutrient ratio of the intake, the maximum level will not appear later than two hours after starting to eat.

Since blood sugar levels need to be monitored consistently to observe changes over time, it is advisable to regularly measure post-meal blood sugar. In tests for diagnosing diabetes, such as the oral glucose tolerance test, and in clinical studies of diabetes, the post-meal blood sugar standard has long been set at "two hours after a meal."