Understanding the Glycemic Index: Which type of potato has the least sugar?

October 18, 2025 •

4 min read

While it may seem that the sweetest potato would have the most sugar, a boiled sweet potato actually has a lower glycemic index (GI) than a boiled white potato. The question of which type of potato has the least sugar? is more complex than it appears, requiring an understanding of glycemic index, a measure of how quickly a food raises your blood sugar.

Quick Summary

This article explores how different potato varieties and cooking methods impact blood sugar levels, using the glycemic index as the key metric. It highlights low-GI options like Carisma and red potatoes, discusses the benefits of resistant starch, and provides tips for incorporating potatoes into a balanced diet to manage blood glucose effectively.

Key Points

Glycemic Index over Sugar Content: The glycemic index (GI), not just simple sugar content, is the key metric for a potato's effect on blood sugar levels.
Waxy Varieties are Lower GI: Waxy potatoes like red, new, and fingerlings have a lower GI than starchy varieties like Russets, leading to a slower blood sugar rise.
Cooling Increases Resistant Starch: Cooking and then cooling potatoes for several hours creates resistant starch, which lowers their GI and lessens their impact on blood sugar.
Cooking Method Matters: Boiling or steaming potatoes is a better option for blood sugar management than baking or frying, which increases the glycemic index.
Balance is Key: To prevent blood sugar spikes, pair potatoes with protein, healthy fats, and fiber-rich vegetables, and practice portion control.
Specialty Options Exist: Varieties like Carisma and purple potatoes are bred or naturally lower in GI, making them excellent choices for controlled carbohydrate intake.

Demystifying Sugar vs. Starch in Potatoes

The most important distinction to understand is the difference between simple sugars and complex starches. While potatoes do contain trace amounts of simple sugars like sucrose and fructose, the vast majority of their carbohydrate content is in the form of starch. Our digestive system breaks down these starches into glucose, which is then released into the bloodstream. The Glycemic Index (GI) is the scale that measures how quickly this conversion and absorption process happens. Foods with a high GI cause a rapid spike in blood sugar, while those with a low GI lead to a slower, more gradual increase.

For example, while a sweet potato might taste sweeter, it often has a lower GI compared to a starchy russet potato, meaning it results in a less significant blood sugar spike. Therefore, focusing solely on the 'sugar' content can be misleading when it comes to managing blood glucose. The better strategy is to consider the overall glycemic impact.

Low-Glycemic Potato Varieties

Several potato types offer a lower glycemic index, making them a more blood sugar-friendly option. These varieties typically have a denser, waxy texture compared to their fluffy, starchy counterparts.

Carisma Potatoes: Often specifically marketed for their lower glycemic load, Carisma potatoes are bred to have fewer total carbohydrates and net carbs per serving. They have a creamy, buttery flavor and are a suitable choice for those managing blood sugar.
Waxy Potatoes (Red and New Potatoes): These varieties, which include red, fingerling, and new potatoes, have a lower starch content and firmer flesh that holds its shape after cooking. They tend to have a medium GI, significantly lower than the starchy Russet.
Purple Potatoes: Beyond their striking color, purple-fleshed potatoes offer a slightly lower GI than white and yellow potatoes. Their vibrant hue comes from anthocyanins, powerful antioxidants that may help lower blood sugar levels.
Sweet Potatoes: The nutritional profile of sweet potatoes includes a lower glycemic index than regular white potatoes, especially when boiled. They are also high in fiber, which contributes to a more gradual rise in blood sugar.

The Impact of Preparation on a Potato's Glycemic Index

The way you cook a potato can have a profound impact on its glycemic response. The cooking process changes the structure of the starches within the potato, which in turn affects how quickly they are digested and absorbed.

Boiling vs. Baking/Frying: Boiling or steaming potatoes generally results in a lower GI compared to baking or frying. The intense, dry heat of baking causes the starch granules to swell and become more digestible, leading to a higher GI. Frying adds fat and calories, creating an even less healthy option.
Cooling and Resistant Starch: A remarkable trick to lower a potato's GI is to cook it and then cool it for at least 12-24 hours. This process increases the amount of resistant starch, a type of carbohydrate that resists digestion in the small intestine. Resistant starch functions like fiber, providing benefits for gut health and leading to a more moderate blood sugar response, even if you reheat the potato. A cooled red potato can have a GI of 56, compared to 89 when eaten hot.
The Skin: Leaving the skin on your potato increases its fiber content, which helps to slow down the absorption of carbohydrates and stabilize blood sugar levels.

Comparison of Common Potato Varieties


Feature	Russet	Red	Sweet Potato	Carisma	Purple
Primary Texture	Starchy, fluffy	Waxy, firm	Soft, creamy	Creamy	Firm, slightly starchy
Glycemic Index (GI)	High (~85-111, baked)	Medium (~60)	Low-Medium (Boiled ~44, Baked ~94)	Low (~53)	Medium-Low
Best Cooking Method	Baking, mashing, frying	Roasting, boiling, salads	Boiling, roasting	Boiling, mashing, baking	Roasting, steaming
Impact on Blood Sugar	Rapid spike	Moderate increase	Slower, more gradual increase	Slowest increase	Slow, gradual increase
Antioxidants	Low	High in skin	High (Beta-carotene)	Moderate	Very High (Anthocyanins)

Dietary Strategy for Potato Consumption

For those concerned about blood sugar, enjoying potatoes doesn't require eliminating them from your diet. Strategic choices and preparation methods can make a significant difference. Here are some key tips:

Pair with Protein and Fiber: A meal with a mix of macronutrients will slow digestion and prevent blood sugar spikes. Pair your potato with a lean protein source (like chicken or fish) and a large serving of non-starchy vegetables (like broccoli or leafy greens).
Add Acidity: Including acidic ingredients like vinegar or lemon juice can help moderate the glycemic response of your meal. A vinaigrette on a potato salad or a sprinkle of vinegar on boiled potatoes is a simple and effective hack.
Cool Cooked Potatoes: Take advantage of the resistant starch effect by boiling your potatoes ahead of time and refrigerating them before serving, or making a cold potato salad.
Control Portion Size: Even a low-GI potato can raise blood sugar if consumed in a large quantity. Adhering to moderate portion sizes is essential for managing blood sugar effectively.
Choose Boiling over Baking or Frying: Opt for healthier cooking methods like boiling, steaming, or microwaving to keep the GI as low as possible.

For further information on managing blood sugar through diet, consulting resources like the Harvard T.H. Chan School of Public Health can be highly beneficial.

Conclusion

In the realm of nutrition, the term 'sugar' can often be misleading, especially with starchy foods like potatoes. The true measure of a potato's impact on blood sugar is its glycemic index. While no standard potato is truly 'low sugar' in the same way as a non-starchy vegetable, opting for low-GI varieties like Carisma, red, or new potatoes is a smart move. Combine this with cooking methods that increase resistant starch, such as boiling and cooling, and remember the importance of portion control and balanced meals. By following these guidelines, you can continue to enjoy potatoes as part of a healthy, blood-sugar-conscious diet.

Frequently Asked Questions

Sweet potatoes actually contain more simple sugar than white potatoes, but they generally have a lower glycemic index, particularly when boiled. Their higher fiber content and the nature of their carbohydrates lead to a slower, more moderate effect on blood sugar levels compared to starchy white potatoes like Russets.

A baked Russet potato can have a very high glycemic index, sometimes over 100, because the high, dry heat makes the starches more easily digestible. Boiling is a much better method for lowering the GI.

When cooked potatoes are cooled, some of their digestible starch converts into resistant starch, which behaves like dietary fiber. This type of starch is not easily digested and absorbed, resulting in a lower glycemic index and a smaller blood sugar spike.

Yes, new potatoes are considered a low-GI option. As waxy potatoes harvested before full maturity, they have less starch and more moisture than mature varieties. This gives them a lower glycemic index and a firmer texture after cooking.

Yes, people with diabetes can eat potatoes as part of a balanced diet. The key is to choose lower-GI varieties (like red, new, or Carisma), use blood-sugar-friendly cooking methods (like boiling and cooling), and practice strict portion control. It is also beneficial to pair them with protein and fiber.

Carisma potatoes are a specific variety bred to have a low glycemic index and lower carbohydrate content than traditional potatoes. They have a creamy texture and are often recommended for those following a low-glycemic diet.

Yes, adding acidic ingredients like vinegar or lemon juice to a meal can help reduce the glycemic response of starchy foods like potatoes. The acetic acid in vinegar helps to slow down the digestion and absorption of carbohydrates.