Sweet potatoes were one of the first New World foods to be accepted in Europe. Many of the yams in supermarkets are actually a type of sweet potato. Since sweet potatoes contain carbohydrates, they can raise blood sugar, but you aren't likely to experience large spikes in blood sugar after eating them due to other compounds found in these tubers.
When carbohydrates go through the digestive process, they are eventually processed into sugars, which are released into your bloodstream. If a lot of sugars are released in a short time, your blood sugar levels spike causing your insulin levels to increase to bring your blood sugar back down. Eating carbs along with protein and fats and choosing carbs that are high in fiber can help keep blood glucose levels from rising too quickly as can watching your portion sizes. Spreading your carbs out evenly throughout the day also helps keep your blood sugar levels where they should be.
Carbs in Sweet Potatoes
A medium sweet potato that is about 5 inches long contains about 24 grams of carbs. This is about 1.5 carb servings, since a serving of carbs for diabetics is 15 grams. Most diabetics can eat between 45 and 65 grams of carbs per meal and still keep their blood sugar levels under control, so a medium sweet potato provides about half of the allowed carbs. Most people should get between 40 and 60 percent of their calories from carbs. Try filling half of your plate with fruits and vegetables and dividing the other half between grains and proteins to get the right amount of carbs in each meal.
The glycemic index is a tool that estimates how much a food is likely to raise your blood sugar levels when it is eaten alone. Foods with a high glycemic index, which means foods with a glycemic index over 70, are likely to cause spikes in your blood sugar, while foods that have a GI below 55 are unlikely to cause blood sugar spikes unless you eat them in large amounts. Even though they are relatively high in carbs, sweet potatoes have a medium glycemic index of 61. This may be due in part to the 3.5 grams of fiber in each medium sweet potato, since fiber can slow the release of sugar into the bloodstream.
Effect on Blood Sugar
Eating sweet potatoes may actually help with blood sugar control, according to a study published in the "International Journal of Agriculture and Biology" in 2008. Researchers measured a decrease in blood sugar levels in participants two hours after they ate sweet potatoes. White-skin sweet potatoes had a larger effect than the Beauregard variety commonly grown and eaten in the United States, and it is best to eat the skin too, since some of the beneficial compounds are found in the skin.
- USDA Nutrient Data Laboratory: Sweet Potato, Cooked, Baked in Skin, Without Salt
- MayoClinic.com: Glycemic Index Diet: What's Behind the Claims
- International Journal of Agriculture and Biology: Impact of Sweet Potato Cultivars on Blood Glucose Level in Diabetic and Healthy Participants
- MayoClinic.com: Diabetes Management: How Lifestyle, Daily Routine Affect Blood Sugar
- Texas A&M University Extension: What's the Difference Between a Sweet Potato and a Yam?
- Oxford Encyclopedia of Food and Drink in America; Andrew F. Smith, editor in chief
- MedlinePlus: Carbohydrates
- U.S. Department of Agriculture: Choose My Plate
Based in Massachusetts, Jessica Bruso has been writing since 2008. She holds a master of science degree in food policy and applied nutrition and a bachelor of arts degree in international relations, both from Tufts University.