Diabetes Alert: Do Starchy Vegetables Spike Your Blood Sugar?

People with diabetes are frequently told to avoid eating potatoes and other starchy vegetables because of the perception that these foods make it difficult to control blood glucose levels. However, when consumed in the context of a well-planned meal, starchy vegetables can safely be part of the diet for people with diabetes.

As the name implies, starchy vegetables contain starch, a type of carbohydrate made from sugar molecules which are linked together in long chains. During digestion, starches are broken down and converted to glucose. The more carbohydrate-containing foods you eat at a meal, the more glucose will enter the bloodstream. Now, don’t misunderstand: This does not mean that you should avoid starchy vegetables. But you will need to monitor your portions and consider the combination of other foods on your plate.

Starchy vegetables such as beans, peas and lentils are packed with nutrients. They are excellent plant protein sources and provide other nutrients such as potassium, iron and zinc. Eating more beans, peas and lentils as part of a healthy diet can help lower blood glucose, blood pressure, heart rate and other heart disease and diabetes risks. A study published in the Archives of Internal Medicine found that people with type 2 diabetes who ate one cup of beans, chickpeas or lentils daily had improved blood glucose control, reduced blood pressure and lower cholesterol levels.

The fiber in beans, peas and lentils slows starch conversion into glucose, which keeps blood glucose levels more stable. Many starchy vegetables contain resistant starch—a type of carbohydrate that resists digestion and doesn’t increase glucose levels. Plantains, green bananas, taro root, beans, peas, lentils and white potatoes all have resistant starch. In clinical studies, vegetables with resistant starch have been shown to stabilize blood glucose levels.

It’s important to be aware that the amount of resistant starch in foods changes with heat. For example, green bananas and plantains lose some of their resistant starch when cooked. On the other hand, a cooked white potato that is cooled is higher in resistant starch.

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The results of a 2020 clinical trial indicate that adults with type 2 diabetes who ate a mixed evening meal with skinless potatoes, had a lower overnight blood glucose response, as compared to a dinner with low-GI basmati rice. Of note, in this study, potatoes which were cooked and cooled produced a low glycemic response. Similarly, consuming warm potatoes with other foods, particularly those higher in fat and protein, will also lower the glycemic response.

How to include starchy vegetables in your diabetes diet:

• Select vegetables with more potassium often, such as sweet potatoes, white potatoes, white beans, soybeans, lima beans, lentils and kidney beans
• Be mindful of cassava, taro and water chestnuts; they are also starchy vegetables
• If you use canned beans, make sure that the label says, “no salt added,” or “low sodium.” Rinse them before you cook them to reduce the sodium content
• Season starchy vegetables with onions, garlic, peppers and herbs instead of salt and fat
• Create a balanced plate. When you get ready to serve yourself a meal, make half the plate non-starchy vegetables such as collards, cabbage or broccoli. Fill a quarter of the plate with your starchy vegetables; the other quarter with your fish, poultry, or meat
• Check your blood glucose two hours after a meal to determine how your body deals with a starchy vegetable or meal

Starchy vegetables are a nutrient power house that can be successfully included in the diet of people with diabetes.

Constance Brown-Riggs is a paid partner of Potatoes USA.