How Long After Eating Does Blood Sugar Peak?
Your blood sugar normally fluctuates within certain safe limits depending on the type of food you eat, how often you eat, your activity levels and certain other health and lifestyle-related factors. Learning how your diet affects your blood sugar, such as how long it takes to reach a peak blood sugar level after a meal, can help you manage or avoid diabetes
DIABETIC VS. NON-DIABETIC
Your blood glucose levels begin to rise within 15 minutes after you start eating a meal and, depending on the type of food and the size of the meal, will peak within around 30 to 45 minutes, says Jennie Brandt, Ph.D., author of “The New Glucose Revolution What Makes My Blood Glucose Go Up . . . and Down?” By three to four hours after your meal, your blood sugar should be back down to the level it was before you started eating. This is known as the fasting level. If you are diabetic, you can expect your blood sugar level to peak a bit later, about an hour after you start eating, and to take longer to return to a fasting level.
Glycemic index — a measurement of the speed at which a particular food affects blood sugar levels — is a useful tool for gauging how quickly the carbohydrates and sugar in your meal will be absorbed into your bloodstream. Moderate glycemic index foods have a glycemic index value around 40 to 70 and include such foods as whole grain breads, brown rice and dairy products. In diabetics, foods with a moderate glycemic index will digest more slowly and cause a milder increase in blood sugar; a peak blood sugar level will occur around one hour after eating, according to certified diabetes educator Gary Sheiner, MS, author of the book “Think Like a Pancreas: A Practical Guide to Managing Diabetes with Insulin.” Foods with low glycemic index result in a very slow and gradual blood sugar rise and may take several hours to reach peak blood sugar levels. These foods have a glycemic value less than 40 and include grapefruit, beans and nuts.
Eating fat or protein along with carbohydrate foods will slow the digestive process, resulting in a slower blood sugar rise and a longer time to return to fasting levels, according to David McCulloch, M.D., author of “The Diabetes Answer Book: Practical Answers to More Than 300 Top Questions.” For instance, a high glycemic meal, such as one that contains mostly processed carbohydrates with little fat or protein, would cause a rapid spike in blood sugar, usually within an hour, and a fast drop. By contrast, a high-fat or high-protein meal would take longer to be released into the bloodstream and would keep blood sugar levels elevated for a longer period of time. The best way to know with certainty how a meal will effect your particular blood sugar levels is to test your blood. Using a glucose meter to measure blood before meals, then measure again each hour after a meal for up to three hours.
The fat portion of your meal may have several potential effects aside from simply slowing the digestive process, says Thomas Wolever, author of the book “The Glycaemic Index: A Physiological Classification of Dietary Carbohydrate.” Additionally, differences in the rates of metabolism of fats and carbohydrates has been found between lean and obese people and between diabetic and non-diabetic people, resulting in a different rate of blood sugar rise and time to reach peak blood sugar levels.