If you don’t have diabetes, you probably don’t give your blood sugar much thought. No matter how much you eat, drink or exercise, your body is going to maintain normal levels of blood glucose (sugar).
But for people with diabetes, managing blood sugar can be a daily struggle. Practically anything and everything can affect blood sugar levels — excess stress, illness, lack of sleep, not enough water, too much or too little exercise, even sunburns. Diet, however, remains one of the main ways people with diabetes can effectively manage their blood sugar, and controlling carb intake is one of the most important aspects of a diabetic-friendly diet.
But not all carbs are created equal. The glycemic index (GI) is one such tool that measures the impact of carbohydrate-containing foods on your blood sugar. Low-glycemic foods are digested more slowly compared to high-glycemic foods, which can raise blood sugar levels fast.
Therefore, it makes sense for people with diabetes or prediabetes to follow a low-glycemic diet, right? Not necessarily, says Kelly Gaines, a registered dietitian nutritionist at Houston Methodist.
“For people with diabetes, there is a benefit to choosing foods that have less of an impact on blood sugar levels,” she says. “A low-glycemic diet has been shown to reduce the risk of type 2 diabetes and coronary heart disease. But just because something is a low-glycemic food doesn’t mean that it’s necessarily a healthy choice.”
While the glycemic index can be a useful tool, it’s not without limitations, according to Gaines, who here explains its benefits, drawbacks and potential alternatives.
What is the glycemic index?
“The glycemic index is a database comparing foods to see how they impact blood sugar or glucose levels,” says Gaines. “The foods are ranked on a scale from 0 to 100 based on how much of an impact they have on blood glucose, zero being the most minimal impact with 100 being the most.”
Low-glycemic foods have a GI between 1 and 55. These foods are digested at a slower rate and are typically — but not always — higher in fiber, protein, fat or a combination of these nutrients, says Gaines. Medium-glycemic foods have a GI between 56 and 69, and high-glycemic foods have a GI from 70 up to 100. High GI foods typically have less fiber, protein or fat and more carbohydrates (sugars), she says. Since the glycemic index measures only carbohydrates (sugar), foods without carbs like meat and fat are not included.
