Lentils are one of the best starchy foods you can eat if you have diabetes. With a glycemic index averaging just 16 for boiled lentils, they raise blood sugar far less than rice, bread, potatoes, or most other carbohydrate sources. They’re also packed with fiber and resistant starch, both of which slow digestion and help keep glucose levels steady after a meal.
Why Lentils Have Such a Low Glycemic Impact
The glycemic index (GI) measures how quickly a food raises blood sugar on a scale from 0 to 100. Boiled lentils average a GI of just 16, placing them firmly in the low category (anything under 55 is considered low). For comparison, white rice typically scores between 70 and 80, and baked potatoes land around 85.
Different types of lentils vary somewhat. Green lentils range from 22 to 37, red lentils from 18 to 32. All remain well within the low-GI range. One exception worth knowing: canned brown lentils score significantly higher, around 42, likely because the canning process breaks down their cellular structure and makes the starch easier to absorb. If keeping blood sugar as stable as possible matters to you, cooking dried lentils will give you the best results.
The glycemic load (GL) of a full one-cup serving of cooked lentils is about 7. Glycemic load accounts for both the speed of sugar absorption and the total amount of carbohydrate in a realistic portion. A GL under 10 is considered low, so even a generous serving of lentils stays in safe territory.
How Lentils Slow Down Sugar Absorption
Three things inside lentils work together to blunt blood sugar spikes. First, lentils are high in soluble fiber, which forms a gel-like substance during digestion that physically slows the rate at which glucose enters your bloodstream. Second, lentils contain a significant amount of resistant starch, a type of starch your body can’t fully break down. Cooked lentils contain about 3% resistant starch by dry weight, and that number jumps to around 5% if you cook them and then let them cool before eating. This means lentil salads and meal-prepped lentils you reheat later may actually be slightly better for blood sugar than freshly cooked ones.
Third, the physical structure of the lentil itself matters. The plant cells in lentils remain relatively intact even after cooking, which means digestive enzymes have to work harder to reach the starch inside. This built-in slow-release mechanism is part of why lentils outperform other starchy foods so dramatically.
The Second Meal Effect
One of the more interesting benefits of lentils is what researchers call the “second meal effect.” When you eat lentils at one meal, your blood sugar response improves not just for that meal but for the next one too. A study published in The American Journal of Clinical Nutrition confirmed that the slow carbohydrate release from lentils continues to influence glucose tolerance hours later. This isn’t because the carbohydrates go unabsorbed. Rather, the gradual digestion keeps insulin working more efficiently into the following meal. Eating lentils at lunch, for example, can help moderate your blood sugar response at dinner.
Replacing Rice or Potatoes With Lentils
You don’t have to eat lentils alone to see a benefit. A randomized crossover trial published in the Journal of Nutrition found that replacing half the carbohydrate from rice with lentils lowered the blood sugar response by about 20%. Swapping half the carbohydrate from potatoes with lentils reduced it by roughly 35%. These are meaningful reductions from a simple substitution. Mixing lentils into rice dishes, using them as a base instead of mashed potatoes, or stirring them into soups alongside smaller amounts of starchier ingredients are all practical ways to apply this.
Portion Size and Carb Counting
Lentils are low-GI, but they’re not low-carb. A half-cup of cooked lentils contains about 20 grams of carbohydrate, which counts as one carbohydrate serving. If you’re tracking carbs per meal, this is the number to work with. Most people with diabetes can comfortably include a half-cup to one cup of cooked lentils in a meal without trouble, but the right amount depends on your individual carb targets and what else is on your plate.
The fiber in that same half-cup (around 8 grams) offsets some of the carbohydrate impact, which is why the glycemic load stays low despite the carb count. Pairing lentils with non-starchy vegetables and a source of protein or healthy fat further flattens the blood sugar curve.
Lentils Within a Diabetes-Friendly Diet
The 2025 Dietary Guidelines Advisory Committee reviewed the evidence on dietary patterns and type 2 diabetes risk and rated the conclusion as “strong”: diets higher in vegetables, fruits, legumes, nuts, whole grains, and fish, and lower in red and processed meats, refined grains, and sugary foods, are associated with lower risk of type 2 diabetes. Lentils fit squarely into this pattern. They’re a core component of both Mediterranean and DASH-style eating, two of the most well-studied approaches for blood sugar management.
Cooking Tips for Maximum Benefit
Cooking lentils thoroughly is the most important preparation step. Boiling significantly reduces lectins, compounds that can irritate the digestive tract when consumed raw or undercooked. Soaking lentils before cooking reduces lectins by a small amount (up to about 5%) and cuts oxalates by 27 to 56%, but cooking itself does the heavy lifting. Unlike beans, most lentil varieties don’t require soaking. Red lentils cook in 15 to 20 minutes, while green and brown varieties take 25 to 35 minutes.
If you want to maximize resistant starch, cook a batch and refrigerate it. Cooling increases resistant starch from about 3% to 5% of dry weight, and reheating doesn’t reverse this change. Batch cooking lentils for the week ahead is both convenient and slightly better for blood sugar control.
Managing Digestive Side Effects
The same fiber that makes lentils so good for blood sugar can cause bloating, gas, or cramping if your body isn’t used to it. The CDC recommends increasing fiber intake gradually rather than jumping straight to large servings. Start with a quarter cup of cooked lentils per meal and work up over a week or two. Drinking plenty of water helps fiber move through your system smoothly.
Red lentils tend to be the easiest to digest because they’re split and hulled, meaning some of the tougher outer fiber has been removed. If green or brown lentils give you trouble, red lentils are a gentler starting point. Rinsing canned lentils thoroughly can also help, though you’ll trade some of the glycemic advantage of cooking from dried.