Whether baked, mashed, fried, boiled, or steamed, potatoes are one of the most popular foods in the human diet.
They’re rich in potassium and B vitamins, and the skin is a great source of fiber.
However, if you have diabetes, you may have heard that you should limit or avoid potatoes.
There are many misconceptions about what people with diabetes should and shouldn’t eat. Many people assume that because potatoes are high in carbs, they’re off-limits if you have diabetes.
The truth is, people with diabetes can eat potatoes in many forms, but it’s important to understand the effect they have on blood sugar levels and the portion size that’s appropriate.
This article tells you everything you need to know about potatoes and diabetes.
How do potatoes affect blood sugar levels?
Like any other carb-containing food, potatoes increase blood sugar levels.
When you eat them, your body breaks down the carbs into simple sugars that move into your bloodstream. This is what’s often called a spike in blood sugar levels.
The hormone insulin is then released into your blood to help transport the sugars into your cells so that they can be used for energy.
In people with diabetes, this process is not as effective. Instead of sugar moving out of the blood and into your cells, it remains in circulation, keeping blood sugar levels higher for longer.
Therefore, eating high-carb foods and/or large portions can be detrimental to people with diabetes.
Poorly managed diabetes is linked to heart failure, stroke, kidney disease, nerve damage, amputation, and vision loss.
Therefore, it’s usually recommended that people with diabetes limit their digestible carb intake. This can range from a very low carb intake of 20–50 grams per day to a moderate restriction of 100–150 grams per day.
The exact amount varies depending on your dietary preferences and medical goals.
Summary: Potatoes spike blood sugar levels as carbs are broken down into sugars and move into your bloodstream. In people with diabetes, the sugar isn’t cleared properly, leading to higher blood sugar levels and potential health complications.
How many carbs are in potatoes?
Potatoes are a high-carb food. However, the carb content can vary depending on the cooking method.
Here is the carb count of 1/2 cup (75–80 grams) of potatoes prepared in different ways:
- Raw: 11.8 grams
- Boiled: 15.7 grams
- Baked: 13.1 grams
- Microwaved: 18.2 grams
- Oven-baked fries (10 steak-cut frozen): 17.8 grams
- Deep-fried: 36.5 grams
Keep in mind that an average small potato (weighing 170 grams) contains about 30 grams of carbs and a large potato (weighing 369 grams) approximately 65 grams. Thus, you may eat more than double the number of carbs listed above in a single meal.
In comparison, a single piece of white bread contains about 14 grams of carbs, 1 small apple (weighing 149 grams) 20.6 grams, 1 cup (weighing 158 grams) of cooked rice 28 grams, and a 12-ounce (350-ml) can of cola 38.5 grams.
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Summary: The carb content of potatoes varies from 11.8 grams in 1/2 cup (75 grams) of diced raw potato to 36.5 grams in a similar serving size of french fries. However, the actual serving size of this popular root vegetable is often much larger than this.
Are potatoes high GI?
A low GI diet can be an effective way for people with diabetes to manage blood sugar levels.
The glycemic index (GI) is a measure of how much a food raises blood sugar compared with a control, such as 3.5 ounces (100 grams) of white bread.
Foods that have a GI greater than 70 are considered high GI, which means they raise blood sugar more quickly. On the other hand, foods with a GI of less than 55 are classed low.
In general, potatoes have a medium to high GI.
However, the GI alone isn’t the best representation of a food’s effect on blood sugar levels, as it doesn’t take into account portion size or cooking method. Instead, you can use the glycemic load (GL).
This is the GI multiplied by the actual number of carbs in a portion, divided by 100. A GL of less than 10 is low, while a GL greater than 20 is considered high. Generally, a low GI diet aims to keep the daily GL under 100.
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Potato variety and the GI and GL
Both the GI and GL can vary by potato variety and cooking method.
For example, a 1 cup (150 gram) serving of potato may be high, medium, or low GL depending on the variety:
- High GL: Desiree (mashed), french fries
- Medium GL: white, Russet Burbank, Pontiac, Desiree (boiled), Charlotte, potato crisps, instant mashed potato
- Low GL: Carisma, Nicola
If you have diabetes, choosing varieties like Carisma and Nicola is a better option to slow the rise of blood sugar levels after eating potatoes.
How to lower the GI and GL of a potato
The way a potato is prepared also affects the GI and GL. This is because cooking changes the structure of the starches and thus how fast they’re absorbed into your bloodstream.
In general, the longer a potato is cooked the higher the GI. Therefore, boiling or baking for long periods tends to increase the GI.
Yet, cooling potatoes after cooking can increases the amount of resistant starch, which is a less digestible form of carbs. This helps lower the GI by 25–28%.
This means that a side of potato salad may be slightly better than french fries or hot baked potatoes if you have diabetes. French fries also pack more calories and fat due to their cooking method.
Additionally, you can lower the GI and GL of a meal by leaving the skins on for extra fiber, adding lemon juice or vinegar, or eating mixed meals with protein and fats — as this helps slow the digestion of carbs and the rise in blood sugar levels.
For example, adding 4.2 ounces (120 grams) of cheese to a 10.2 ounce (290 gram) baked potato lowers the GL from 93 to 39.
Keep in mind that this much cheese also contains 42 grams of fat and will add nearly 400 calories to the meal.
As such, it’s still necessary to consider the overall number of carbs and the quality of the diet, not just the GI or GL. If controlling weight is one of your goals, your total calorie intake is also important.
Summary: A low GI and GL diet can be beneficial for people with diabetes. Potatoes tend to have a medium to high GI and GL, but cooled cooked potatoes, as well as varieties like Carisma and Nicola, are lower and make a better choice for people with diabetes.
Risks of eating potatoes
Although it’s safe for most people with diabetes to eat potatoes, it’s important to consider the amount and types you consume.
Eating potatoes both increases your risk of type 2 diabetes and may have negative effects on people with existing diabetes.
One study in 70,773 people found that for every 3 servings per week of boiled, mashed, or baked potatoes, there was a 4% increase in the risk of type 2 diabetes — and for french fries, the risk increased to 19%.
Additionally, fried potatoes and potato chips contain high amounts of unhealthy fats that may increase blood pressure, lower HDL (good) cholesterol, and lead to weight gain and obesity — all of which are associated with heart disease.
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This is particularly dangerous for people with diabetes, who often already have an increased risk of heart disease.
Fried potatoes are also higher in calories, which can contribute to unwanted weight gain.
People with type 2 diabetes are often encouraged to maintain a healthy weight or lose weight to help manage blood sugar and reduce the risk of complications.
Therefore, french fries, potato chips, and other potato dishes that use large amounts of fats are best avoided.
If you’re having trouble managing your blood sugar levels and diet, speak with a healthcare provider, dietitian, or diabetes educator.
Summary: Eating unhealthy potato foods, such as chips and french fries, increases your risk of type 2 diabetes and complications, such as heart disease and obesity.
Good replacements for potatoes
Although you can eat potatoes if you have diabetes, you may still want to limit them or replace them with healthier options.
Look for high fiber, lower carb, and low GI and GL foods like the following:
- Carrots and parsnips. Both are low GI and GL and have less than 10 grams of carbs per 2.8-ounce (80-gram) serving. They’re great boiled, steamed, or baked.
- Cauliflower. This vegetable is an excellent alternative to potato either boiled, steamed, or roasted. It’s very low in carbs, making it a terrific option for people on a very low-carb diet.
- Pumpkin and squash. These are low in carbs and have a low to medium GI and a low GL. They’re a particularly good replacement for baked and mashed potatoes.
- Taro. This root is low in carbs and has a GL of just 4. Taro can be sliced thinly and baked with a little oil for a healthier alternative to potato chips.
- Sweet potato. This veggie has a lower GI than some white potatoes and varies between a medium and high GL. These tubers are also a great source of vitamin A.
- Legumes and lentils. Most foods in this category are high in carbs but have a low GL and are rich in fiber. However, you should be careful with serving sizes as they still increase blood sugar levels.
Another good way to avoid large portions of high-carb foods is to fill at least half of your plate with non-starchy vegetables, such as broccoli, leafy greens, cauliflower, peppers, green beans, tomatoes, asparagus, cabbage, Brussels sprouts, cucumbers, and lettuce.
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Summary: Lower carb replacements for potatoes include carrots, pumpkin, squash, parsnip, and taro. High carb but lower GI and GL options include sweet potato, legumes, and lentils.
Potatoes are a versatile and delicious vegetable that can be enjoyed by everyone, including people with diabetes.
However, because of their high carb content, you should limit portion sizes, always eat the skin, and choose low GI varieties, such as Carisma and Nicola.
In addition, it’s best to stick with boiling, baking, or steaming and avoid fried potatoes or potato chips, which are high in calories and unhealthy fats.
If you’re struggling to make healthy choices to manage your diabetes, consult your healthcare provider, dietitian, or diabetes educator.