Glycemic index and diabetes
Glycemic index (GI) is a measure of how quickly a food can make your blood sugar (glucose) rise. Only foods that contain carbohydrates have a GI. Foods such as oils, fats, and meats do not have a GI, though in people with diabetes, they can affect the blood sugar.
In general, low GI foods increase glucose slowly in your body. Foods with a high GI increase blood glucose quickly.
If you have diabetes, high GI foods can make it harder to control your blood sugar.
Diabetes is on the rise worldwide, and is a serious, lifelong disease that can lead to heart disease, stroke, and lasting nerve, eye and foot problems. Let's talk about diabetes and the difference between the three types of diabetes. So, what exactly is diabetes and where does it come from? An organ in your body called the pancreas produces insulin, a hormone that controls the levels of your blood sugar. When you have too little insulin in your body, or when insulin doesn't work right in your body, you can have diabetes, the condition where you have abnormally high glucose or sugar levels in your blood. Normally when you eat food, glucose enters your bloodstream. Glucose is your body's source of fuel. Your pancreas makes insulin to move glucose from your bloodstream into muscle, fat, and liver cells, where your body turns it into energy. People with diabetes have too much blood sugar because their body cannot move glucose into fat, liver, and muscle cells to be changed into and stored for energy. There are three major types of diabetes. Type 1 diabetes happens when the body makes little or no insulin. It usually is diagnosed in children, teens, or young adults. But about 80% of people with diabetes have what's called Type 2 diabetes. This disease often occurs in middle adulthood, but young adults, teens, and now even children are now being diagnosed with it linked to high obesity rates. In Type 2 diabetes, your fat, liver, and muscle cells do not respond to insulin appropriately. Another type of diabetes is called gestational diabetes. It's when high blood sugar develops during pregnancy in a woman who had not had diabetes beforehand. Gestational diabetes usually goes away after the baby is born. But, still pay attention. These women are at a higher risk of type 2 diabetes over the next 5 years without a change in lifestyle. If you doctor suspects you have diabetes, you will probably have a hemoglobin A1c test. This is an average of your blood sugar levels over 3 months. You have pre-diabetes if your A1c is 5.7% to 6.4%. Anything at 6.5% or higher indicates you have diabetes. Type 2 diabetes is a wake up call to focus on diet and exercise to try to control your blood sugar and prevent problems. If you do not control your blood sugar, you could develop eye problems, have problems with sores and infections in your feet, have high blood pressure and cholesterol problems, and have kidney, heart, and problems with other essential organs. People with Type 1 diabetes need to take insulin every day, usually injected under the skin using a needle. Some people may be able to use a pump that delivers insulin to their body all the time. People with Type 2 diabetes may be able to manage their blood sugar through diet and exercise. But if not, they will need to take one or more drugs to lower their blood sugar levels. The good news is, people with any type of diabetes, who maintain good control over their blood sugar, cholesterol, and blood pressure, have a lower risk of kidney disease, eye disease, nervous system problems, heart attack, and stroke, and can live, a long and healthy life.
Information
Not all carbohydrates work the same in the body. Some trigger a quick spike in blood sugar, while others work more slowly, avoiding large or rapid rises in blood sugar. The glycemic index addresses these differences by assigning a number to foods that reflects how quickly they increase blood glucose compared to pure glucose (sugar).
The GI scale goes from 0 to 100. Pure glucose has the highest GI and is given a value of 100.
Eating low GI foods can help you gain tighter control over your blood sugar. Paying attention to the GI of foods can be another tool to help manage your diabetes, along with carbohydrate counting. Following a low-GI diet also may help with weight loss.
Glycemic Index of Certain Foods
Low GI foods (0 to 55):
- Bulgur, barley
- Pasta, parboiled (converted) rice
- Quinoa
- High-fiber bran cereal
- Oatmeal, steel-cut or rolled
- Carrots, non-starchy vegetables, greens
- Apples, oranges, grapefruit, and many other fruits
- Most nuts, legumes, and beans
- Milk and yogurt
Moderate GI foods (56 to 69):
- Pita bread, rye bread
- Couscous
- Brown rice
- Raisins
- Honey
- Pineapple
High GI foods (70 and higher):
- White bread and bagels
- Most processed cereals and instant oatmeal, including bran flakes
- Most snack foods
- Potatoes
- White rice
- Sugar
- Watermelon
Meal Planning with the Glycemic Index
When planning your meals:
- Choose foods that have a low to medium GI.
- When eating a high GI food, combine it with low GI foods to balance the effect on your glucose levels. The GI of a food, and its impact on people with diabetes may change when you combine it with other foods.
The GI of a food is affected by certain factors, such as the ripeness of a piece of fruit. So, you need to think about more than the GI of a food when making healthy choices. When choosing meals, it's a good idea to keep these issues in mind.
- Portion size still matters because calories still matter, and so does the amount of carbohydrates. You need to keep an eye on the portion size and number of carbohydrates in the meal you are having, even if it has low GI foods.
- In general, processed foods have a higher GI. For example, fruit juice and instant potatoes have a higher GI than whole fruit and whole baked potatoes.
- Cooking can affect the GI of a food. For example, al dente pasta has lower GI than soft-cooked pasta.
- Foods higher in fat or fiber tend to have a lower GI.
- Certain foods from the same class of foods can have different GI values. For example, converted long-grain white rice has a lower GI than brown rice. And short-grain white rice has a higher GI than brown rice. Likewise, quick oats or grits have a high GI but whole oats and whole-grain breakfast cereals have a lower GI.
- Choose a variety of healthy foods keeping in mind the nutritional value of the whole meal as well as the GI of foods.
- Some high GI foods are high in nutrients. So balance these with lower GI foods.
For many people with diabetes, carbohydrate counting, or carb counting, helps limit carbohydrates to a healthy amount. Carb counting along with choosing healthy foods and maintaining a healthy weight may be enough to regulate diabetes and lower the risk for complications. But if you have trouble regulating your blood sugar or want tighter control, you should talk with your health care provider about using the glycemic index as part of your action plan.
References
American Diabetes Association Professional Practice Committee. 5. Facilitating Positive Health Behaviors and Well-being to Improve Health Outcomes: Standards of Care in Diabetes-2024. Diabetes Care. 2024;47(Suppl 1):S77-S110. PMID: 38078584
MacLeod J, Franz MJ, Handu D, et al. Academy of Nutrition and Dietetics Nutrition practice guideline for type 1 and type 2 diabetes in adults: nutrition intervention evidence reviews and recommendations. J Acad Nutr Diet. 2017;117(10)1637-1658. PMID: 28527747
Version Info
Last reviewed on: 10/11/2024
Reviewed by: Frank D. Brodkey, MD, FCCM, Associate Professor, Section of Pulmonary and Critical Care Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
