Carbs in Potatoes: Are They Good for Diabetics?

Carbs in baked potato

Portion	Carbs	Fiber	Net carbs	Sugar	Calories
Medium potato173 g	37 g	4 g	33 g	2 g	161
Small potato138 g	29 g	3 g	26 g	2 g	128
Large potato299 g	63 g	7 g	57 g	4 g	278

Per 100 g: 21.1 g carbs, 2.2 g fiber, 2.5 g protein, 0.1 g fat, 93 calories. Source: USDA FoodData Central (Potatoes, baked, flesh and skin, without salt). Net carbs = carbs minus fiber. Brands and recipes vary, so check the label when you have one.

The short version

A medium baked potato (173 g, with skin) has about 37 g of carbs, with about 4 g of fiber. A large one has about 63 g.
Yes, people with diabetes can eat potatoes. Count them as a starchy carb, like rice or bread, not as a vegetable you can pile on.
Most potatoes raise blood sugar quickly. Cooking them ahead and eating them cold or reheated tends to slow that down.
Keep the portion to about the size of your fist, keep the skin on, and eat them with protein and other vegetables.

How many carbs are in a potato?

The size of the potato decides most of the number. USDA data for a baked potato eaten with its skin gives 21.1 g of carbs per 100 g. That works out to:

Small (138 g): about 29 g of carbs
Medium (173 g): about 37 g of carbs
Large (299 g): about 63 g of carbs

The baked potatoes served in restaurants and steakhouses are often the large size or bigger, and the toppings come on top of that. If you're not sure, weigh one after cooking once. After that you can judge by eye much better.

Other ways of cooking land in a similar range. Boiled potato (flesh only) has 20.1 g of carbs per 100 g, so half a cup of boiled potato pieces (78 g) is about 16 g and a whole boiled potato of about 136 g is about 27 g. Homemade mashed potato with milk and butter has 16.8 g per 100 g, because the milk and butter dilute it, which makes one cup (210 g) about 35 g of carbs.

Only about 4 g of a medium potato's carbs are fiber. If your care team has you count net carbs, a medium baked potato is about 33 g. Our carb counting guide explains portions, labels and fiber if you're just starting.

Are potatoes good for diabetics?

Potatoes are not off limits. The American Diabetes Association doesn't ban single foods. It looks at the total carbs in a meal and the quality of those carbs. A plain potato with its skin gives you potassium, vitamin C and some fiber, and it isn't processed.

The catch is that potatoes are mostly starch, with little fiber to slow it down. Per 100 g, a baked potato has about the same carbs as a baked sweet potato (21.1 g and 20.7 g), but less fiber. So the real question is how much you eat and how you cook it. Fries and chips are a different story: frying adds a lot of fat, and the portions tend to be large.

What potatoes do to blood sugar

Potatoes tend to raise blood sugar fast. A Canadian study measured the glycemic index of common North American potatoes and found a wide range depending on the type and the cooking:

Boiled red potatoes eaten hot: 89, and instant mashed potatoes: 88. Both are high.
Baked Russet potatoes: 77, and roasted white potatoes: 72. Moderately high.
Boiled red potatoes eaten cold: 56, which is in the medium range.

The same study found that Russet potatoes cooked ahead, refrigerated and reheated raised blood sugar less than ones cooked and eaten right away. Starch that cools after cooking changes into a form that's digested more slowly. The effect is modest. The carb count stays the same.

In real meals, a potato eaten alongside chicken, fish or a salad will likely rise more slowly than a potato eaten on its own. Your own meter or CGM is the best guide. Check before you eat and about 2 hours after you start, and compare a few different potato meals. Our guide to blood sugar 2 hours after eating covers what the numbers mean.

How to eat potatoes with diabetes

Watch the size. One small potato, or half a large one, is a sensible portion for most meals.
Cook ahead. Potato salad made with cooled potatoes, or leftovers reheated the next day, tends to cause a slower rise than freshly cooked potatoes.
Keep the skin. It adds fiber. Scrub it well and bake, boil or roast it whole.
Fill the rest of the plate. Protein and non-starchy vegetables slow things down and help you feel full on a smaller potato.
Count the toppings. Butter, sour cream and cheese add fat, which can push the rise later. Baked beans or a sweet sauce add more carbs.
Be careful with instant mash and fries. Instant mashed potato was among the fastest in the study, and fries come in big portions with a lot of oil.

Want meals with fewer carbs overall? See our list of low-carb meals for diabetes.

If you take insulin Count the carbs in your potato like any starchy food. Fast-rising potatoes and high-fat potato dishes can both change the shape of the rise. Your insulin-to-carb ratio and timing should come from your doctor or diabetes educator, so ask your care team rather than relying on an article.

Counting it without a scale

Most days you won't weigh your potato. In T1dApp you take a photo of your plate and get the carbs for each food on it, including the potato, as a range you can edit. Two hours later the app asks for your reading, so you can see how potatoes, cooked your way, actually affect you.

Snap your meal, see the carbs

T1dApp gives you carbs, calories, protein and fat from a photo, and your likely blood sugar 2 hours later.

Get T1dApp

Sources

This article is general information, not medical advice. Your targets, doses and diet should be set with your doctor or diabetes care team.

Carbs in potatoes, and are they good for diabetics?