Written by Amy Brownstein, MS, RD
If you’re at risk of developing or already have type 2 diabetes, you may be concerned about whether you can eat carbohydrates like pasta, rice, and potatoes. Recommendations for managing prediabetes and diabetes may suggest reducing carbohydrate intake. But carbohydrates are essential to the diet, providing vital nutrients and energy. Certain cooking methods can lower the glycemic response (the extent to which carbohydrate-containing foods raise blood sugar) of carbohydrates, making them more favorable for your blood sugar levels and allowing you to continue enjoying carbohydrates like potatoes, pasta, and rice.
Read on to learn about different cooking methods that can alter the glycemic effect of carbohydrates.
Resistant Starch Reduces the Glycemic Index
Resistant starch is the non-digestible starch found in carbohydrates. Digestive enzymes cannot break down resistant starch, so it travels through the gastrointestinal system undigested. Ultimately, resistant starch ends up intact in the large intestine, where gut bacteria ferment it. Resistant starch helps reduce the glycemic index (GI) (a rating scale used to assess the effect of carbohydrates on blood sugar levels) of pasta, rice, and potatoes, making these foods more favorable for your blood sugar.
Can you change the amount of starch in food?
You can change the amount of resistant starch in food through retrogradation. In retrogradation, starches that have separated during cooking reform. Certain processes — particularly cooling starches after they have cooked — can contribute to retrogradation. Starches broken down by cooking are easier to digest. Conversely, when the cooked food is chilled, the starches reform and once again become indigestible. This reduces the glycemic effect of the food. Furthermore, repeated rounds of cooling and reheating may create progressively more resistant starch, thus having a more beneficial effect on blood sugar. 
How Can You Lower the Glycemic Response of Carbohydrates?
Blood sugar levels naturally increase after you eat carbohydrates. But it is possible to lower this glycemic response to some carbohydrates. Research shows that increasing the resistant starch of potatoes, rice, and pasta (typically through cooling processes that lead to retrogradation), results in a lower glycemic response so that you can keep these foods in your diet.
Chilling potatoes can lower the glycemic response
Though many factors (for example, farming practices, the type of potato, storage, cooking method, and serving temperature) may influence potatoes’ resistant starch content, we will focus on one particular approach: cooking and then cooling potatoes.
Research shows that cooked then chilled potatoes have more resistant starch (one study found 3 grams more resistant starch per 100-gram serving) than cooked potatoes.  This change in resistant starch (when cooked potatoes are cooled before consumption) may reduce the postprandial glucose response by nearly 40 percent.  Another study in women who were overweight with elevated fasting blood sugar and insulin levels also supports these results. Study investigators found that consuming eight ounces (one cup) of cooked then chilled potatoes resulted in lower postprandial glucose (after the meal) and insulin levels than eating hot boiled potatoes. 
Cool and reheat white rice for better blood sugar control
You may have been told to limit the rice you eat with type 2 diabetes. While portion size is important, changing your cooking method can help improve your glycemic response to rice.
Similar to potatoes, cooking then cooling white rice can reduce its effect on blood sugar levels. One small study evaluated the effects of different preparation methods of white rice on blood sugar levels. Researchers found that cooking, cooling the white rice for 24 hours at 39F (about the temperature of your refrigerator), and reheating resulted in a lower glycemic response than eating the rice either immediately after cooking or after cooling it for 10 hours at room temperature. 
How to lower the glycemic index of pasta
Pasta can be an easy weeknight meal for many people. Luckily, there are many techniques for improving the glycemic response to pasta, so you don’t need to eliminate this food from your diet.
Like potatoes and rice, cooking then cooling pasta may lower the glycemic response. One study among people in their early 20s without insulin resistance found that both chilled (24 hours at 39F) and reheated pasta elicited a better glucose response (quicker return to normal levels following a meal) than freshly cooked, hot pasta. Moreover, the reheated pasta resulted in a more significant reduction in blood sugar than the hot pasta. 
Are There Other Ways You Can Change the Glycemic Response to Carbohydrates?
While cooking, then cooling potatoes, rice, and pasta significantly affects the glycemic response, other methods exist to help reduce the impact of carbohydrates on blood sugar levels.
Use whole-grain or bean-based pasta
Opt for whole-grain pasta or pasta made from legumes like chickpeas or lentils. These types of pasta have a higher fiber content, which can slow digestion and reduce the glycemic response. Whole-grain pasta is also richer in nutrients compared to refined white pasta.
Cook pasta al dente
Cooking pasta al dente, which means cooking until it is firm to the bite, can help lower its glycemic response. Al dente pasta takes longer to digest, resulting in a slower release of glucose into the bloodstream.
Incorporate vinegar or lemon juice
Adding a small amount of vinegar or lemon juice to cooked pasta, potato, and rice dishes can help reduce the glycemic response. The acid slows down the digestion of carbohydrates and lowers the rate at which glucose is released into the bloodstream.
Add vegetables to the dish
Mixing cooked pasta, potatoes, or rice with various non-starchy vegetables can increase the fiber content and lower the glycemic response. Saute or steam vegetables like broccoli, spinach, bell peppers, or zucchini and combine with pasta, potatoes, or rice.
Combine with protein and healthy fats
Including a source of lean protein, such as tempeh, tofu, or legumes, and healthy fats, like olive oil or avocado, can help slow down the absorption of carbohydrates from pasta, potatoes, and rice and reduce the overall glycemic response.
Tips for Managing Blood Sugar Levels When Eating Potatoes, Rice, or Pasta
Potatoes, white rice, and pasta can all be part of a healthy diet to reverse type 2 diabetes. Try these tips for incorporating potatoes, white rice, and pasta into your diet to help reduce the glycemic response to these carbohydrate sources.
- Cook, then chill your potatoes, rice, or pasta before eating. Chill the food in the refrigerator for at least a few hours for best results.
- The glycemic response may vary depending on the type of potato or rice. Experiment with different potato or rice varieties to see how each affects your blood sugar. Opt for varieties with a lower glycemic index, such as sweet potatoes or red potatoes, instead of high-GI potatoes like russet or white potatoes.
- Cook your pasta al-dente and try different types of pasta, such as chickpea, black bean, edamame, mung bean, and whole wheat. These different types of pasta contain more fiber (which lowers the glycemic response) than typical pasta.
- Include fiber and protein sources with your pasta, potatoes, and rice for an additional benefit on blood sugar.
Experiment with these different tips to see what works best for you. As we all have different glycemic responses to food, you may find one method works best for you.