How Food Affects Your Blood Glucose

Reviewed and updated by Di Bush, PhD

Whether you have type 1 or type 2 diabetes, what you eat, when you eat it and how much you eat all affect your blood glucose. Glucose is the main sugar found in the blood and is the body’s major source of fuel.

If you have diabetes and eat too much or do not take the right dose of diabetes medicine, your blood glucose can spike too high. When this happens, you can get sick.

If your blood glucose stays high for too long, a condition called hyperglycemia, you may be at risk for heart, eye, foot, kidney or other problems. Blood glucose that goes too low, also known as hypoglycemia, can be caused by not taking the right amount of diabetes medicine, and can also cause diabetes-related problems.

You can prevent or slow down diabetes-related problems by keeping your blood glucose at a healthy level. Your healthcare team can help you set goals for where your blood glucose level should be to stay healthy and will let you know how often you should check your blood glucose. The results from these checks will tell you if your diabetes care plan is working. Also, ask your doctor for an A1C test at least twice a year so you will know what your blood glucose levels have been like for the most part of the past three months. The A1C test can tell you more about the health status of your diabetes than daily blood glucose testing alone.

Doing certain things, such as those listed below, at the same time each day will help keep your blood glucose at a healthy level:

  • Eat about the same amounts of food at about the same times each day.  Your blood glucose goes up after you eat, so if you eat a big lunch one day and a small lunch the next day, your blood glucose levels will change too much.

  • Do not skip meals or snacks.

  • Take your medicines and exercise at about the same times each day.

  • Eat about the same amounts of higher carbohydrate foods, or carbs, at about the same times each day. Carbs are found in starchy foods such as bread, rice, and pasta as well as fruits, dairy products, and starchy vegetables, such as corn, potatoes, and peas. Sugary sweets and juices are high in carbs, so should be eaten very rarely by diabetics and in small portions. Talk with a dietitian or someone else on your healthcare team to find out about how many meals and snacks you should eat each day.
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