Do Potatoes Spike Blood Sugar | Potatoes Glycemic Index

Glycemic index of potatoes: All you need to know

When it comes to the glycemic index (GI) of potatoes, there are a few key things worth knowing. The glycemic index measures how carbs in food affect blood sugar levels. Potatoes, a staple in many diets, have a range of GI values depending on several factors. Let’s dive in and uncover all the details of these starchy tubers!

Potato variety and glycemic index 

The glycemic index of potatoes is influenced by several factors, including variety. Not all potatoes are created equal in terms of their impact on blood glucose levels. Different potato varieties have different amounts of starch that can influence their GI. 

Here are the average glycemic index of different potato varieties:

• Russet Burbank: 82 (1)
• Desiree: 74 (1)
• Carisma: 53 (1)
• Nicola: 59 (2)
• Estima: 66 (2)
• King Edward: 75 (2)
• Red potato: 89 (3)
• White potato: 82 (4)

Despite being a popular variety, the russet potato glycemic index is among the highest. GI values above 70 are considered high, between 56-69 are medium, and values ≤ 55 are classified as low (5).

Cooking method and its impact

The preparation and cooking methods of potatoes are important factors that can affect their glycemic index. Some common methods used for cooking potatoes are baking, frying, boiling, and roasting (6). These cooking methods modify potato structure chemically at different levels, thus impacting the glycemic index (6).

A study shows some examples of the cooking method’s effects on GI (7):

• Boiled potato: 78
• Instant mashed potato: 87
• French fries: 63
• Boiled sweet potato: 63

However, some studies show that these GI values can be lowered by cooling the potatoes (8, 9). For example, the hot-boiled red potato glycemic index is 89.4, while the cold one is only 56.2 (8). This cooling process increases the amount of resistant starches in potatoes. The resistant starches act as fiber, which won’t be digested as sugar, and thus results in lower GI (10). 

Potatoes with the lowest glycemic index

Opting for potatoes with low glycemic index can be an excellent choice to manage blood sugar levels. Varieties like Carisma, Nicola, and sweet potatoes are considered to have lower glycemic index than other varieties. Boiling and then allowing them to cool can help maintain their lower glycemic index. Pairing them with protein-rich foods, vegetables, or healthy fats can also help reduce the overall glycemic response (11). 

The glycemic index of mashed potatoes

Due to the preparation method, mashed potatoes generally have a high glycemic index of around 108 (11). Mashing potatoes increases their gelatinization and surface area, which may lead to faster digestion of carbohydrates (12, 13, 14).  

Adding fats or sugars to mashed potatoes can further raise the glycemic load. However, it’s worth noting that the overall glycemic impact also depends on other ingredients and portion sizes.

Do potatoes spike blood sugar? Potatoes and diabetes 

Although potatoes naturally contain a minimal amount of sugar, they’re not primarily known for their sugar content. Potatoes are a source of starch, a carbohydrate that our body breaks down into sugar (15). This process will spike our blood sugar levels. Therefore, the glycemic index focuses on the rate at which the starch is converted into glucose rather than the presence of sugar itself (16). 

Even though potatoes are technically low in sugar, they can have a high GI value due to the starch conversion into sugar. For the same reason, it can affect blood sugar levels and may increase the risk of type 2 diabetes.  

However, it’s important to note that carbohydrate conversion happens gradually during digestion. The process is even slower when the potatoes are consumed along with other food components. As a result, glucose absorption into the blood will slow down, reducing the risk of rapid spikes in blood sugar levels for people with diabetes.

Best ways to eat potatoes for people with diabetes

Including potatoes in a diabetes-friendly diet should be done carefully to maintain stable blood sugar levels. Here are some recommended approaches to enjoying potatoes while considering their glycemic impact. 

Choosing the right variety and cooking method

Opting for the low GI variety and the proper cooking process could significantly impact the glycemic index of the potatoes that we consume. Carisma and Nicola varieties are suggested as they are considered low-GI potatoes (1, 2). 

Although the study results are varied, some of the recommended potato cooking methods are boiling and baking. It’s even better when served after cooling, as the resistant starch increases when cooled, which lowers the GI (8). 

Mind portion sizes

Pay attention to portion control when consuming potatoes. Although baked or boiled potatoes might have a lower glycemic impact, excessive eating can still affect blood sugar levels. It’s best to monitor portion sizes and be mindful of overall carbohydrate intake. Consulting a nutritionist can provide personalized guidance on appropriate portions that align with dietary needs.

Pair with balanced components

To further minimize the impact of potatoes on blood glucose levels, try to include other foods to create a balanced meal. Pairing potatoes with protein-rich foods, vegetables, and healthy fats can help slow digestion down; thus, it may reduce the overall glycemic response (17, 18).