Does Chocolate Raise Your Blood Sugar?

A young woman sits on a set of stairs outside and eats a bar of chocolate while looking at her phone.
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As long as you choose flavonoid-rich dark chocolate, the sweet treat could have a number of beneficial effects on health, including lowering your blood pressure and your risk for heart disease. The beneficial compounds in dark chocolate may also help minimize your diabetes risk, according to a study published in "The Journal of Nutrition" in February 2014. However, this doesn't mean eating a lot of chocolate won't have an effect on your blood sugar. The composition of a food, the portion size you eat and when you eat it can all make a difference in the effect of a food on your blood sugar levels.

Carbohydrate Content

Because of their different composition, some types of chocolate have a greater effect on blood sugar than others. Out of the three macronutrients, carbohydrates have the greatest effect on blood sugar; however, if a food also contains a significant amount of fat or protein, these nutrients slow down the absorption of the sugars from the food and lessen the impact of the food on your blood sugar. Dark chocolate has 12.9 grams of carbohydrates per ounce, which is slightly less than the typical 15 grams considered a serving of carbohydrates for diabetics. Milk chocolate and white chocolate are higher in carbohydrates, with about 16.8 grams per ounce, so they'll have more of an impact on your blood sugar if you eat too much of them.

Glycemic Index and Glycemic Load

Glycemic index is a tool used to help estimate the potential effect of a food on blood sugar levels. Pure sugar has a glycemic index of 100. Foods that are high on the glycemic index are more likely to cause spikes in blood sugar levels than those lower on the glycemic index. Dark chocolate has a glycemic index of 23, and milk chocolate has a glycemic index of 42. These are both within the low range because they are below 55. When serving size is taken into account to determine the overall glycemic load, however, dark chocolate has a clear advantage. Dark chocolate has a low glycemic load, with a score of 6, but milk chocolate has a moderate GL, with a score of 13, meaning it is more likely to cause an increase in blood sugar levels.

Potential Diabetes Benefits

The 2014 "Journal of Nutrition" study found that eating foods containing certain flavonoids, including those found in dark chocolate, may help reduce insulin resistance, one of the beginning signs of Type 2 diabetes. This doesn't mean that eating a lot of chocolate will prevent diabetes, but you may not have to worry that eating a small amount of dark chocolate from time to time is going to increase your diabetes risk.

As Part of a Healthy Diet

Choose dark chocolate instead of milk or white, as dark chocolate is highest in beneficial flavonoids. Limit your portion size -- you only need to eat about an ounce of dark chocolate once or twice a week to get the potential health benefits, according to an article on the AARP website. Eating too much chocolate could increase your risk for weight gain because it is relatively high in calories. An ounce of dark chocolate has about 167 calories.