Dietary glycemic index and glycemic load in relation to HbA1c in Japanese obese adults: a cross-sectional analysis of the Saku Control Obesity Program

Abstract

BackgroundDietary glycemic index or load is thought to play an important role in glucose metabolism. However, few studies have investigated the relation between glycemic index (GI) or load (GL) and glycemia in Asian populations. In this cross-sectional analysis of a randomized controlled trial, the Saku Control Obesity Program, we examined the relation between the baseline GI or GL and glycemia (HbA1c and fasting plasma glucose [FPG] levels), insulin resistance (HOMA-IR), β-cell function (HOMA-β), and other metabolic risk factors (lipid levels, diastolic and systolic blood pressure, and adiposity measures).MethodsThe participants were 227 obese Japanese women and men. We used multiple linear regression models and logistic regression models to adjust for potential confounding factors such as age, sex, visceral fat area, total energy intake, and physical activity levels.ResultsAfter adjustments for potential confounding factors, GI was not associated with HbA1c, but GL was positively associated with HbA1c. For increasing quartiles of GI, the adjusted mean HbA1c were 6.3%, 6.7%, 6.4%, and 6.4% (P for trend = 0.991). For increasing quartiles of GL, the adjusted mean HbA1c were 6.2%, 6.2%, 6.6%, and 6.5% (P for trend = 0.044). In addition, among participants with HbA1c ≥ 7.0%, 20 out of 28 (71%) had a high GL (≥ median); the adjusted odds ratio for HbA1c ≥ 7.0% among participants with higher GL was 3.1 (95% confidence interval [CI] = 1.2 to 8.1) compared to the participants with a lower GL (<median). Further, among 16 participants with FPG ≥ 150 mg/dL, 13 participants (81.3%) had a higher GL; the adjusted odds ratio for FPG ≥ 150 mg/dL among participants with a higher GL was 8.5 (95% confidence interval = 1.7 to 43.4) compared to those with a lower GL. In contrast, GI and GL were not associated with metabolic risk factors other than glycemia.ConclusionsOur findings suggest that participants with poor glycemic control tend to have a higher GL in an obese Japanese population.

High Fiber and Low Starch Intakes Are Associated with Circulating Intermediate Biomarkers of Type 2 Diabetes among Women

“…However, in this cross-sectional analysis of healthy postmenopausal women, higher cereal fiber intake and lower starchto-cereal fiber and carbohydrate-to-cereal fiber intake were associated with lower concentrations of HbA1c. Among healthy adults, 2 cross-sectional studies found no association between whole grain intake and HbA1c concentrations, but 1 among obese Japanese adults found a positive association between GL (not GI) and HbA1c concentrations, which we did not observe in our study (10,39,40). Among adults with T2D, a meta-analysis of 10 randomized controlled trials of fiber supplementation lasting from 3 to 12 wk found that participants in the fiber intervention arm, overall, had a reduction in HbA1c of 0.26% more than the reduction in control participants (41).…”

“…Conventional measures of carbohydrate quality such as total fiber, cereal fiber, whole grains, and low glycemic index (GI) and glycemic load (GL) intakes have been consistently associated with a lower risk of T2D (5)(6)(7)(8). GL has been inversely associated with adiponectin concentrations among US men (9) and positively associated with HbA1c concentrations in Japanese adults (10). Total fiber intake has been inversely associated with CRP (11)(12)(13) concentrations in a nationally representative US study and in 2 other cohorts of US adults, but was not associated with CRP in a study among postmenopausal women (14).…”

Dietary glycemic index, glycemic load and incidence of type 2 diabetes in Japanese men and women: the Japan public health center-based prospective study

“…Considering that rice is a high GI food and that it is the major source of carbohydrates in Japanese diets, the current result seems reasonable, as the dietary GL reveals both the quantity and quality of carbohydrates in diets. A cohort study in Chinese women also reported a positive association between the dietary GL and the risk of diabetes [ 14 ], and a recent cross-sectional study of obese males and females in Japan reported an association between the dietary GL and the HbA1c level [ 37 ]. No association was observed between the dietary GL and the risk of diabetes among men.…”

Impact of High-Carbohydrate Diet on Metabolic Parameters in Patients with Type 2 Diabetes

“…The average dietary GI was 66 ± 5, and the average dietary GL was 79 ± 17 (1000 kcal). They showed that GI was not associated with HbA1c, but GL was positively associated with HbA1c [ 62 ]. For increasing quartiles of GI, the adjusted mean HbA1c were 6.3%, 6.7%, 6.4% and 6.4% ( p for trend = 0.991); whereas, for increasing quartiles of GL, the adjusted mean HbA1c were 6.2%, 6.2%, 6.6% and 6.5% ( p for trend = 0.044).…”