Glycemic index, glycemic load and their association with glycemic control among patients with type 2 diabetes

The aim was to investigate the associations of glycemic index (GI), glycemic load (GL), carbohydrate and fiber intakes with hyperglycemia in type 2 diabetic patients.

In a cross-sectional study of 640 type 2 diabetic patients aged 28-75 years, usual dietary intakes were assessed by validated food frequency questionnaire. We used published international and Iranian tables of GI based on the white bread. Multivariable logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CI).

High-GL diet was associated with higher risk of hyperglycemia in type 2 diabetic patients after controlling for potential confounders. In multivariable model, OR (95% CI) for the highest vs the lowest quartile of GL was 2.58 (1.08-6.15) for elevated fasting serum glucose (FSG) (>130 mg/dl) (P(trend) = 0.02) and was 3.05 (1.33-7.03) for elevated HbA1c (>8.6%) (P(trend)=0.008). After additional adjusting for dietary fiber and protein intakes, the relation of GL with elevated FSG and HbA1c was stable. GI was not significantly associated with either elevated FSG or HbA1c. In multivariable model, OR (95% CI) for the highest vs lowest quartile of the substitution of dietary carbohydrate for fat intake was 2.32 (1.37-3.92) for elevated HbA1c (P(trend) = 0.001). Higher intake of dietary fiber was associated with lower risk of elevated FSG (highest vs lowest quartile: OR, 0.53; 95% CI: 0.28-0.99; P(trend) = 0.04), but not with lower risk of elevated HbA1c.

GL and carbohydrate intake were positively associated with the risk of hyperglycemia in type 2 diabetic patients; but the benefit in pursuing a low-GI diet without considering carbohydrate and energy intakes in these patients should be further investigated.