Do low-glycemic diets benefit patients with diabetes?

This study examined if low-glycemic index (GI) diets can help improve symptoms of diabetes and pre-diabetes. This study concluded that low-GI diets might help reduce blood sugar levels and body weight in these patients.

Patients with pre-diabetes, T1D, or T2D have difficulty controlling their blood glucose levels. The glycemic index (GI) of a food is used to assess how that food will affect blood glucose levels. Low GI foods increase blood glucose levels more slowly than high GI foods.

Several studies have shown that low GI foods can help improve glucose control. In a low GI diet, a person eats carbohydrates that are slower to digest, such as rice, bread, and vegetables, and avoids processed, sugary foods. Whether a low GI diet can help improve glucose control in patients with pre-diabetes, T1D, or T2D is under investigation.

This study used data from 54 studies that evaluated a low GI diet in patients with Type 1 diabetes (T1D), Type 2 diabetes (T2D), or pre-diabetes. These studies assessed several health factors. These included HbA1c levels (average blood glucose over the past 3 months) and fasting blood sugar (levels of glucose in the blood after several hours without food). Insulin levels, cholesterol levels, body weight, and BMI (a measure of obesity) were also measured.

Overall, a low GI diet significantly reduced HbA1c levels by 0.15 points. Fasting blood sugar levels were significantly reduced by 1.67 mg/dL. Patients with T2D had a significant drop in fasting blood sugar levels (1.7 mg/dL).

A low GI diet also significantly reduced total cholesterol levels by 4.5 mg/dL. In patients with pre-diabetes, this decreased by 6.4 mg/dL.  LDL cholesterol (the type of cholesterol implicated in heart disease) was also reduced by 5.5 mg/dL.  HDL cholesterol and triglyceride levels were not affected by a low GI diet.

Body weight was not directly affected by a low GI diet. However, patients who had a healthy body weight had a significantly higher decrease in fasting blood sugar levels compared to patients who were overweight (4.3 mg/dL vs. 2.4 mg/dL). Overall, BMI was reduced by 0.6 kg/m². Patients with obesity had a significant decrease in their BMI (1.8 kg/m²).

Insulin levels and insulin resistance were not affected by a low GI diet.

This study concluded that a low GI diet could help reduce blood sugar levels, total cholesterol levels, and BMI in patients with diabetes or pre-diabetes. The authors suggest that patients with T2D may especially benefit from this diet, but whether low GI diets help lower body weight remains unclear.

This study used retrospective data. This means that the study looked back in time to analyze data. The studies used in this analysis had a short follow-up time (1 week to 12 months). Also, there were very few studies that examined T1D. More studies are needed to confirm these results.

Talk to your doctor about your diet options, including the low GI diet.