healthy nutrition

Why do potatoes have a higher glycemic index than sugar?

Did you know that potatoes have a relatively high glycemic index (GI)? The GI indicates the extent to which certain foods cause blood sugar levels to rise. Each type of potato has a different index value, but for the majority it is between 80 and 90.

Why potatoes raise blood sugar

Potatoes have a high glycemic index

Potatoes are a staple food and appear in many German dishes. But people who watch their blood sugar should eat them in moderation because potatoes, like foods containing sugar, have a very high GI value. Why is that? The reason is quite simple: the starch in potatoes is converted into sugar in our body.

The starch in potatoes

The starch in potatoes has a negative effect on blood sugar

Too often, glucose is associated with sweetness. White potatoes are generally not considered to be sweet. However, potatoes contain almost exclusively starch, and starch is made up of long chains of glucose molecules.

Because the starch in potatoes is digested quickly, the glycemic index of potatoes can be almost as high as that of glucose alone. The glycemic index of glucose is 100 points, while the GI of potatoes usually varies between 80 and 90. However, potatoes have a higher GI value than table sugar. How is that possible?

A sucrose molecule consists of a proportion of glucose and fructose

Pure sucrose (table sugar) has a GI of 65 to 70. A sucrose molecule consists of a proportion of glucose (grape sugar or dextrose) and fructose (fruit sugar). Fructose is processed differently in the body than glucose and does not affect blood sugar as much.

When you consider that 30 grams of carbohydrates from potatoes contain twice as much glucose as sugar, it is only logical that they would have a greater impact on blood sugar levels than table sugar.

Not all potatoes are created equal, however, and there are ways to reduce their effects on your blood sugar. You can still enjoy potatoes from time to time, but in moderation.

Factors influencing the GI of potatoes

Factors influencing the GI of potatoes


There are many varieties of potatoes and it would be incorrect to say that every potato has a glycemic index of 80 or 90. In fact, researchers have found that the glycemic index can only be as high as 53 for some varieties of potato.

In one study, the researchers tested seven varieties of potatoes: Russet Burbank, Mayflower, Nicola, Bintje, Carisma, Desiree and Virginia Rose. They found that the Carisma potato had a GI of 53, making it the only one in the group to be classified as a low GI variety. With 69 GI, Nicola fell into the medium GI category. The Russet Burbank variety potatoes, which are very popular, ranked highest with 82 GI.

Different types of potato have a different glycemic index

In general, the GI of potatoes can range from 53 to 111, with white potatoes typically ranking lower in the index. Not peeling the potatoes can reduce the effect on glucose levels. Often the sweet potato is rated with a GI value of around 40.

Cooking method

Eat baked potatoes with spices as a side dish

The way you prepare your potatoes, including the cooking method and ingredients added, can have an impact on glycemic effects. A study published by the Journal of the American Dietetic Association looked at how different cooking methods affect the glucose response of potatoes.

The researchers found that the way potatoes are cooked plays a big role. They advised consumers to pre-cook potatoes and eat them cold or warmed up if they wanted to minimize glycemic effects.

A ready-made instant mashed potato and boiled red potatoes elicited the highest glycemic response. Fried potatoes showed a slightly lower glycemic response.

You should eat less potatoes?

potato nicola glycemic index low

There are several factors to consider when deciding whether or not to include potatoes in your low GI diet.

Different people have different glycemic responses to different foods. The most important factor is how your own body reacts to potatoes. You can get this information with a blood glucose meter. This is especially important if your body is not processing sugar optimally or you have been diagnosed with prediabetes. High blood sugar levels are not unique to diabetics and can cause serious problems.

It depends on the portion size

A serving of potatoes is around 150 grams or a fist-sized potato

Potatoes provide the body with important nutritional values. A serving of potatoes is about 150 grams The glycemic load (or the glycemic response) depends on how much of it you eat and what other foods you ingest with the potatoes. Most of the time, potatoes are eaten as a side dish to the main course, which changes the effects on your blood sugar.

For example, you should eat meat with a small potato and a salad to keep the meal balanced. The other foods can actually decrease the potatoes’ effect on your glucose.

Same goes for low GI foods like beans and lots of vegetables. Combining potatoes with lots of healthy fat, protein, or fiber will also reduce the glucose effects.

Eating potatoes as a side dish will prevent blood sugar from rising


Since potatoes can be high in glucose, think about what you can do to reduce it. If you want to eat potatoes, choose a variety of potatoes with a lower GI, eat smaller portions, and combine potatoes with foods that counteract glucose. Most importantly, keep an eye on your blood sugar and see how these changes affect you personally.

Potatoes and blood sugar levels - a balanced diet is important