Potatoes and diabetes: cooking changes everything
The short answer
Yes, a person with diabetes can eat potatoes, but how they are cooked changes everything. Boiled in water, their average glycaemic index (GI) measured in people with diabetes is 53, low to moderate. Mashed, it rises to 71, baked to 76, and instant mash to 86: high GIs, close to glucose. A 200 g portion of boiled potatoes provides 34 g of carbohydrate. The good habit: boiled or steamed potatoes, 150 to 200 g, with vegetables and a protein, and chips (French fries) as an exception. Cooling cooked potatoes, in a salad for example, also lowers their GI.
This guide gives general guidance. If you are treated with insulin or with a medicine that can cause hypoglycaemia (low blood sugar), your carbohydrate amount per meal should be set with your doctor or dietitian.
The potato: a starchy food, not a vegetable
For the PNNS (the French national nutrition and health programme), the potato counts among the starchy foods, with bread, rice and pasta, and not among the vegetables. This matters for a person with diabetes: on the plate, it replaces the rice or pasta, it is not added to it. The GEMRCN, the reference for catering in canteens and institutions, provides for 200 to 250 g of cooked potatoes per adult as a side dish, as for rice and pasta.
What a portion contains depending on the cooking
| 200 g of potatoes | Calories | Carbohydrate | Fibre | Fat | Potassium |
|---|---|---|---|---|---|
| New potatoes, boiled | 143 kcal | 30.0 g | 3.2 g | 0.6 g | 860 mg |
| Boiled in water | 162 kcal | 33.6 g | 3.6 g | 0.7 g | 726 mg |
| Oven-baked | 183 kcal | 38.0 g | 4.4 g | 0.3 g | 1,070 mg |
| Mash, with milk and butter | 190 kcal | 31.4 g | 3.0 g | 4.8 g | 520 mg |
| Pan-fried, with fat | 274 kcal | 34.6 g | 5.2 g | 11.4 g | 1,360 mg |
| Chips (French fries), deep-fried | 516 kcal | 65.4 g | 7.8 g | 23.8 g | 1,368 mg |
Chips stand out clearly: by losing water during cooking, they concentrate the carbohydrate, twice as much as boiled potatoes for the same weight, and they absorb oil. 200 g of chips provide as much carbohydrate as 400 g of potatoes boiled in water. For 30 g of crisps, count 15 g of carbohydrate, 10 g of fat and 0.4 g of salt.
Glycaemic index: what the studies measure in people with diabetes
The international glycaemic index tables (Atkinson, Foster-Powell and Brand-Miller, 2008) contain many measurements of potatoes in people with diabetes, for a 150 g portion:
| Preparation | Glycaemic index | Number of studies |
|---|---|---|
| New potatoes | 47 and 54 | 2 |
| Boiled in water | 53 on average (24 to 85) | 7 |
| Tinned, reheated | 61 | 1 |
| Homemade mash | 71 on average | 3 |
| Frozen chips, reheated | 75 | 1 |
| Baked | 76 on average | 3 |
| Microwaved | 82 | 1 |
| Instant mash | 86 on average | 4 |
Why such differences? The starch in potatoes gelatinises during cooking: the longer, drier or more mechanical the cooking, the more accessible it is to digestive enzymes. Mash, which is crushed, and baked potato, cooked for a long time right through to the core, are digested very quickly. New potatoes, which are firmer, stay the lowest. The variety matters too: waxy potatoes generally do better than floury ones. For the notion of GI, see our guide to the glycaemic index.
The cooled potato trick
In a single Lebanese study, boiled potatoes had a GI of 85 served hot and 54 once cooled. As they cool, part of the starch reorganises into resistant starch, which the small intestine does not digest. A potato salad, prepared in advance and served cold, therefore raises blood sugar much less than hot mash.
Cooling, reheating, adding vinegar: what two other studies show
The effect of cooling does not rest on a single study. Two trials, carried out in Canada and Sweden, confirm it and clarify what matters in the kitchen.
- In Canada (Fernandes et al., Journal of the American Dietetic Association, 2005), boiled red potatoes had a GI of 89 eaten hot and 56 eaten cold. In the same study, roasted potatoes had a GI of 72, baked Russets 77 and instant mash 88. Cooking the day before, refrigerating and then reheating lowered the glycaemic response of Russet potatoes, but not that of boiled white potatoes: reheating therefore does not guarantee the same benefit as a dish served cold.
- In Sweden (Leeman et al., European Journal of Clinical Nutrition, 2005), 13 volunteers without diabetes ate boiled potatoes, either fresh or kept for 24 hours in the fridge at 8 °C. The cold raised resistant starch from 3.3% to 5.2% of total starch, and lowered the insulin response by 28%. With a dressing added, 8 g of olive oil and 28 g of white vinegar, the glycaemic index fell by 43% and the insulin response by 31% compared with fresh, hot potatoes.
The practical lesson: potato salad prepared the day before, served cold with a vinaigrette, is the gentlest form of potato for blood sugar. These trials involve volunteers without diabetes or small numbers of people; the exact effect in you may vary, but the direction is consistent from one study to the next.
Work out the glycaemic load of your portion
| Portion | Carbohydrate | Glycaemic index | Glycaemic load |
|---|---|---|---|
| 150 g boiled | 25.2 g | 53 | 13 |
| 200 g boiled | 33.6 g | 53 | 18 |
| 200 g new potatoes, boiled | 30.0 g | 47 to 54 | 14 to 16 |
| 200 g homemade mash | 31.4 g | 71 | 22 |
| 200 g baked | 38.0 g | 76 | 29 |
| 150 g of chips | 49.1 g | 75 | 37 |
A portion of boiled potatoes has a moderate load. The same amount baked or mashed has a high load, and a portion of chips is more than double that of potatoes boiled in water.
Potatoes and the risk of diabetes: what the studies say
- A meta-analysis of six cohorts (Bidel et al., 2018) linked each daily portion of potatoes to a risk of type 2 diabetes that was 20% higher, all preparations combined.
- A more recent analysis of seven American cohorts, more than 105,000 people (Djoussé et al., 2024), found no association for boiled, baked or mashed potatoes, but a risk that was 12% higher in those who ate fried potatoes more than once a week.
The message that emerges: it is not so much the potatoes themselves as chips and large portions that are the problem. Potatoes boiled in water, in a reasonable amount, have their place in a diet suited to diabetes.
Replacing some of the potatoes: what a large study says
A third study complements the two presented above. It followed 199,181 American health professionals, in three cohorts, for 20 to 26 years depending on the cohort (Muraki et al., Diabetes Care, 2016). Of these, 15,362 developed diabetes.
- Eating potatoes 7 times a week or more was associated with a risk of diabetes that was 33% higher than eating them less than once a week. Between 2 and 4 times a week, the difference was not significant.
- For each increment of three portions a week, the risk increased by 4% for baked, boiled or mashed potatoes, and by 19% for chips.
- Replacing three portions of potatoes a week with the same amount of wholegrain cereals was associated with a risk that was 12% lower.
Like other work of this kind, these are observational studies, which show an association and not a cause. Their message agrees with that of the previous section: it is chips and frequency that weigh most. In practice, there is no need to cut them out: between 2 and 4 times a week, no clear excess risk appeared. On the other days, alternate with lentils, bulgur, wholemeal bread or brown rice.
For 20 g of carbohydrate: the equivalent depending on the preparation
If your dietitian has given you an amount of carbohydrate per meal, here is the weight of potatoes that corresponds to 20 g of carbohydrate. The difference between preparations is striking.
| Preparation | Carbohydrate per 100 g | Weight for 20 g of carbohydrate |
|---|---|---|
| Tinned, drained | 10.7 g | 187 g |
| Flake mash, made with semi-skimmed milk and water | 12.4 g | 161 g |
| New potatoes, boiled | 15.0 g | 133 g |
| Homemade mash, milk and butter | 15.7 g | 127 g |
| Boiled in water | 16.8 g | 119 g |
| Oven-baked | 19.0 g | 105 g |
| Chips (French fries), deep-fried | 32.7 g | 61 g |
| Plain crisps | 51.0 g | 39 g |
| Reduced-fat crisps | 61.4 g | 33 g |
Two traps stand out. Flake mash seems low in carbohydrate because it contains a lot of water, but its GI is the highest of all, 86 on average: weight does not tell the whole story. And « reduced-fat » crisps contain more carbohydrate than ordinary crisps, 61.4 g against 51.0 g per 100 g: it is fat that has been removed, not starch.
Good habits
- Boiled or steamed, with the skin on when possible, rather than baked, mashed or as chips.
- 150 to 200 g, in place of the bread, rice or pasta in the meal, not on top of it.
- With vegetables and a protein: fish, eggs, meat, pulses, and a drizzle of oil.
- Cooled in a salad, with a vinaigrette: the resistant starch lowers the GI.
- Not overcooked: a potato that holds its shape is digested more slowly than one that falls apart.
For other starchy foods, see our guides lentils and diabetes, how much rice per person and how much pasta per person.
What about sweet potato?
Sweet potato is not necessarily better: Ciqual gives it 16.3 g of carbohydrate per 100 g cooked, the same as boiled potato, and its GIs measured in people with diabetes range from 59 to 78 depending on the variety and the cooking. It does provide a little more fibre, 2.9 g against 1.8 g per 100 g. Eat it in the same amounts.
Special cases
Kidney failure
Potato is rich in potassium, more than 700 mg for 200 g boiled. In kidney disease, the nephrologist may advise peeling them, cutting them up and cooking them in plenty of water, which reduces their potassium, and limiting portions.
Gestational diabetes
During pregnancy, prefer boiled or steamed potatoes, in a moderate portion, and avoid mash and chips every day. See eating during pregnancy.
Weight loss
200 g of boiled potatoes gives 162 kcal, less than 200 g of cooked pasta, 334 kcal. It is the cooking fat and the accompaniments that make the difference: 200 g of chips gives 516.
3 ideas for eating them
- Potato salad: served cold with a mustard vinaigrette, with herbs and an egg.
- Steamed new potatoes, with their skin, a salmon fillet and green beans.
- Baked potatoes: to keep for occasions, in a 150 g portion, with a large salad.
More ideas in our low glycaemic index recipes.
Our potato recipes, in carbohydrate per serving
The values below are calculated from Ciqual for each ingredient in our recipes. They help you choose the right recipe and the right serving.
- Potato salad with vinaigrette: 39 g of carbohydrate per serving, for 200 g of potatoes. This is the preparation that the studies above favour: cold and with vinegar. For a meal, half a serving with an egg and a green salad is often enough.
- Potato and herring salad: 32 g of carbohydrate and 14 g of protein per serving: a complete dish.
- Light potato tortilla: 30 g of carbohydrate and 14 g of protein per serving, thanks to the six eggs.
- Leek and potato soup: 26 g of carbohydrate and 8 g of fibre per bowl. Blended, it is drunk quickly: add a protein on the side.
- Light gratin dauphinois: 36 g of carbohydrate per serving, as much as the classic gratin dauphinois (35 g). The light version divides the fat by seven, 2 g against 15 g, but not the carbohydrate.
Frequently asked questions
Can someone with diabetes eat potatoes?
Yes, preferably boiled or steamed, 150 to 200 g, in place of another starchy food. Their average GI in people with diabetes is 53 boiled, against 76 baked.
Which way of cooking potatoes is best for someone with diabetes?
In water or steamed, without overcooking, and ideally cooled in a salad. Mash, baking, microwaving and instant mash have high GIs.
Is mash not recommended?
Its average GI is 71, and 86 for instant mash. It is not forbidden, but it is the form that raises blood sugar the most: a small portion, with vegetables and protein.
Are chips forbidden?
Not forbidden, but best kept for occasions: 150 g provides 49 g of carbohydrate and 18 g of fat, and eating them more than once a week is associated with a higher risk of diabetes.
Potato or rice for someone with diabetes?
Weight for weight, boiled potatoes provide half the carbohydrate of cooked white rice, 16.8 g against 33.2 g per 100 g. Lentils do even better.
Why eat potatoes cold?
As they cool, part of the starch becomes resistant: in one study, the GI went from 85 to 54 between hot and cooled potatoes.
Does vinegar lower the GI of potato?
In a Swedish trial, cooled potatoes served with a vinaigrette had a GI 43% lower than fresh, hot potatoes. Cold and vinegar work together.
Can you reheat cooled potatoes?
Yes, but the benefit is less certain. In a Canadian study, cooking the day before and then reheating reduced the glycaemic response of one variety, but not that of boiled white potatoes. Served cold, the effect is clearer.
Are reduced-fat crisps better for someone with diabetes?
Not for blood sugar: they contain 61.4 g of carbohydrate per 100 g, against 51 g for ordinary crisps. They have less fat, but more starch.
The foods and diabetes series
Glycaemic index, glycaemic load and the right portion, food by food: apple and diabetes, pear and diabetes, orange and diabetes, banana and diabetes, grapes and diabetes, dates and diabetes, melon and diabetes, strawberries and diabetes, pineapple and diabetes, cheese and diabetes, mango and diabetes, honey and diabetes, dark chocolate and diabetes, lentils and diabetes, avocado and diabetes, oats and diabetes, bread and diabetes, kiwi and diabetes, sweet potato and diabetes, rice and diabetes.
Going further
Lentils and diabetes, glycaemic index, type 2 diabetes: diet and prevention, potato nutrition facts.
Our sources
- Atkinson FS, Foster-Powell K, Brand-Miller JC. International Tables of Glycemic Index and Glycemic Load Values: 2008. Diabetes Care, 2008.
- Bidel Z et al. Potato consumption and risk of type 2 diabetes: A dose-response meta-analysis of cohort studies. Clinical Nutrition ESPEN, 2018.
- Djoussé L et al. Potato Consumption and Risk of Type 2 Diabetes Mellitus: A Harmonized Analysis of 7 Prospective Cohorts. Journal of Nutrition, 2024.
- PNNS (Santé publique France): potato among the starchy foods; GEMRCN: portion weights for cooked starchy foods.
- Table Ciqual 2025 (Anses): potatoes by cooking method, chips, crisps, mash, sweet potato, cooked rice and pasta.
- Fernandes G, Velangi A, Wolever TM. Glycemic index of potatoes commonly consumed in North America. Journal of the American Dietetic Association, 2005. PMID 15800557.
- Leeman M, Ostman E, Björck I. Vinegar dressing and cold storage of potatoes lowers postprandial glycaemic and insulinaemic responses in healthy subjects. European Journal of Clinical Nutrition, 2005. PMID 16034360.
- Muraki I, Rimm EB, Willett WC, Manson JE, Hu FB, Sun Q. Potato Consumption and Risk of Type 2 Diabetes: Results From Three Prospective Cohort Studies. Diabetes Care, 2016. PMID 26681722.
- Table Ciqual 2025 (Anses): tinned potato, flake mash, plain and reduced-fat crisps. Recipes on the site: values per serving calculated from Ciqual.
