Glycemic Index and Diabetes: What’s the Connection?
Glycemic Index (GI) and Diabetes
The glycemic index is a tool to help people with diabetes improve blood glucose control (1).
While a low glycemic index diet can benefit healthy individuals, research has found that the larger the divergence of glucose metabolism from the norm, the larger the effect of low glycemic index and glycemic load interventions (2).
Type 2 Diabetes
Research has found low GI diets to lead to improved insulin sensitivity, glucose control and lipid profile, and a decreased risk of hypoglycemic episodes and other complications of type 2 diabetes (3, 4, 5).
Lowering the dietary GI without changing carbohydrate intake or body weight has been shown to improve peripheral insulin sensitivity. A low GI diet can also significantly improve glucose utilization, total cholesterol, and low-density lipoprotein levels (4).
A low GI diet is associated with decreased glycated hemoglobin levels, which leads to a reduced risk of hypoglycemic events. Compared with a high GI diet, a low GI diet significantly reduces hypoglycemic episodes (5).
Hypoglycemic episodes occur when blood sugar falls below normal levels. High GI foods cause a blood glucose spike, followed by an insulin spike, which leads to a quick decrease in blood glucose levels. However, this doesn't always necessarily indicate that hunger will be activated since insulin has an anorexigenic effect as well. There are different metabolic responses that are getting triggered at the same time that keep the body in metabolic balance.
For people at high risk, studies suggest replacing high GI forms of carbohydrates with low GI carbohydrates to reduce the risk of type 2 diabetes (6).
Low GI diets can be effective for weight loss in people with normal glucose tolerance. However, research finds that in people with impaired glucose tolerance or type 2 diabetes, a low GI diet alone is insufficient to achieve weight loss (7).
Type 1 Diabetes
There is overall less research regarding the effects of a low glycemic index diet in patients with type 1 diabetes.
Studies have found that using the glycemic index to guide food choices can help improve glycemic control to a clinically significant degree in type 1 diabetes patients.
A consistent low glycemic index diet may reduce insulin requirement while improving blood glucose control. However, blood glucose levels should be carefully monitored, and insulin doses should be adjusted if necessary (8, 9).
That being said, UK’s National Clinical Guideline Centre finds more research is necessary to recommend a low glycemic index diet to type 1 diabetes patients as a method for glucose control (10).
Gestational diabetes is the development of diabetes during pregnancy, which disappears after childbirth.
Research has not found significant effects of a low GI diet on the metabolic profile, pregnancy outcomes, insulin resistance, or glucose tolerance compared to a moderate GI diet in people with gestational diabetes (11).
In intensively monitored women at risk for gestational diabetes, a low GI diet and a healthy diet produce similar pregnancy outcomes (12).
If interested, you can visit our glycemic index definition page to learn about the glycemic index, how it’s calculated, classified, and more.