Determining the relationship between dietary carbohydrate intake and insulin resistance

Abstract

Insulin resistance underlies type 2 diabetes, CVD and the metabolic syndrome, driven by changes in diet, lifestyle, energy over-consumption and obesity. Nutritional recommendations for insulin resistance remain an area of controversy, particularly the quantity and types of dietary carbohydrate. The present review gives an overview of insulin resistance, its relationship to impaired insulin secretion and the metabolic syndrome, research methodologies used to measure insulin action and the epidemiological and intervention studies on the relationship between dietary carbohydrate and insulin resistance. Epidemiological studies provide little evidence to suggest that total dietary carbohydrate predicts risk of type 2 diabetes, and high-carbohydrate, high-fibre diets with low-glycaemic index (GI) may even contribute to diabetes prevention. Despite inherent limitations associated with techniques used to measure insulin resistance and dietary assessment, most intervention studies reveal an increase in glucose tolerance or insulin sensitivity with highcarbohydrate, low-fat diets in non-diabetic and diabetic individuals. When energy is restricted the source or reduced content of carbohydrate does not appear to be as important as fat for body weight. Thus, low energy intake is key to weight loss and augmentation of insulin sensitivity. Given this, widespread adoption of popular low-carbohydrate high-fat diets highlights the necessity to evaluate dietary interventions regarding safety and metabolic effects. While current evidence supports FAO/WHO recommendations to maintain a highcarbohydrate diet with low-GI foods, the relationships between carbohydrate and insulin sensitivity remains an important research area. Emerging technologies should further enhance understanding of gene -diet interactions in insulin resistance, providing useful information for future nutrition policy decisions.

Scientific Opinion on Dietary Reference Values for carbohydrates and dietary fibre

“…Some small scale and short-term intervention studies designed to assess the effects of high carbohydrate (50 to 85%E), low fat (<25E%) vs low carbohydrate (8 to 40%E), high fat (>35%) intakes on measures of glucose tolerance or insulin sensitivity suggest that high carbohydrate intakes may improve insulin sensitivity and/or glucose tolerance both in non-diabetic and diabetic subjects (McClenaghan, 2005), although the available data are not consistent (IoM, 2005).…”

Increased Insulin Resistance and Glucagon Levels in Mild/Inactive Systemic Lupus Erythematosus Patients Despite Normal Glucose Tolerance

“…First, no control for important confounding factors known to significantly affect insulin sensitivity, such as physical activity levels (16), body composition (17), and food intake (18), was provided in these studies, which might have influenced these results. Second, fasting insulin levels and HOMA IR are static estimates thought to primarily reflect hepatic insulin sensitivity as they rely on basal steady-state measures of glucose and insulin (5,19).…”

Effect of Eucaloric High- and Low-Sucrose Diets With Identical Macronutrient Profile on Insulin Resistance and Vascular Risk

“…These results therefore cannot be extrapolated to humans taking more palatable levels of sucrose or fructose. Studies in human subjects show variable effects with alterations of dietary sucrose intake when using simple measures of insulin sensitivity (16). One small study in seven subjects without diabetes demonstrated that a high-glycemic index diet (25% sucrose) was associated with detrimental effects on insulin sensitivity compared with a low-glycemic index diet (1.2% sucrose) over 4-week dietary periods (17).…”