Diabetes Forecast

6 Steps to Avoiding Blood Glucose Spikes

Do some experimenting to discover how meals affect blood glucose levels

By Erika Gebel, PhD , ,

Predicting how much blood glucose levels will rise or fall in response to meals involves a few variables. These include how much and what you eat, and the amount of insulin in your blood (whether your own, injected, or pumped). Every person's body is a little bit different in how it turns various kinds of food into energy and in how it uses that energy. People with diabetes who'd like to learn more about food and lowering their blood glucose levels can become scientists specializing in their own bodies. Ready to put on your lab coat?

Why Test?

Not every person with diabetes needs to embark on an odyssey of self-discovery. But, apart from curiosity, there are good reasons why it might be time to do some experimenting. "If your A1C [average blood glucose level over the previous two to three months] isn't where you want it to be, then you need to look at what's happening throughout the day," says Monica Joyce, MS, RD, LDN, CDE, of Sobel Medical Associates in Chicago. Joyce also recommends taking some readings if you're trying to lose weight, as the types of foods you eat and your body size may change, affecting blood glucose levels. Starting a new medication or stopping one are also reasons for extra glucose testing.

Science Experiment

  • Clean, dry fingers
  • Lancing device

  • Lancet

  • Test strips

  • Glucose meter

  • Logbook (paper or digital)


  1. Test first thing in the morning; write down the number.
  2. Test immediately before your meal; write down the time and the number.
  3. Test again one to two hours after the first bite of your meal; write down the time and the number.
  4. Log what you eat, including the type, quantity, and carbohydrate content of foods. 
  5. Write down any factors besides food that might influence blood glucose (medication, exercise, stress, illness, etc.).
  6. Test before bed.

Note: Wait at least four hours between meals, without snacking in between. If you're taking insulin, however, and need to snack to keep blood glucose levels from dipping too low, do so.

The Protocol

Joyce suggests keeping a close eye on what you eat and your blood glucose levels for a couple of weeks at a time to get a sense of blood glucose behavior. If your access to test strips is limited, ask your health care provider for a prescription for test strips or the strips themselves. Then, try experimenting for just four or five days, making sure to include weekdays with routine meals and weekends that feature your favorite foods. To get a complete blood glucose picture of a meal, you'll need two blood glucose checks: one before and one after you eat.

Data Analysis

A general goal blood glucose level for one to two hours after a meal, according to the American Diabetes Association, is under 180 mg/dl; some experts recommend lower targets—ask your provider what's best for you. If your data reveal that it's frequently going much higher than that, Joyce says, you can look into adjusting things.

  • Portions Perfected: On the plus side, you may not have to give up the foods you like. You can reduce the portion of an item rather than give it up, says Joyce: "No one wants to take favorite foods away from people." Besides trimming portion sizes, choose healthful fruits, vegetables, and whole grains rather than foods with added sugar for your carbohydrate choices.
  • Medication Management: If your data show that blood glucose levels are high before meals or in the morning (fasting blood glucose), it may indicate that your medication needs to be adjusted to reach blood glucose targets. "The four-hour period of time between meals should have given the insulin or medication the time to bring the blood sugar down to normal," says Joyce. You and your provider can use this information to fine-tune medication, particularly insulin, based on blood glucose levels before the next meal. Joyce says premeal testing can also help people trying to control their blood glucose with diet alone see if their approach is working.

Tips to Treat: After-Meal Highs

To get blood glucose levels back down under 180 mg/dl within an hour or two after a meal, experiment with these tactics:

Count calories. Monica Joyce, MS, RD, LDN, CDE, suggests rigorously monitoring calorie and carbohydrate intake for a week or so. That will help identify if you're eating more than you thought and cement in your mind what an appropriate portion size looks like.

Eat high-fiber foods. Some evidence suggests that high-fiber foods, such as beans, whole grains, and some vegetables, can blunt blood glucose increases. Plus, they're extra filling, so they'll help you eat less.

Take enough insulin. If you use mealtime insulin, ask your provider if your premeal dose is adequate for the number of carbohydrate grams you're consuming. Also discuss how to calculate a correction dose and when one may be necessary. If your premeal blood glucose is high, work on that first.

Take a 30-minute walk after eating. This can help people with type 1 or type 2 diabetes burn some extra glucose from a meal.



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