The American journal of clinical nutrition
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Review Meta Analysis
Glycemic response and health--a systematic review and meta-analysis: the database, study characteristics, and macronutrient intakes.
Reduction of dietary glycemic response has been proposed as a means of reducing the risk of diabetes and coronary heart disease. Its role in health maintenance and management, alongside unavailable carbohydrate (eg, fiber), is incompletely understood. ⋯ Among GI studies, observed reductions in glycemic load are most often not solely due to substitution of high for low glycemic carbohydrate foods. Available carbohydrate intake is a confounding factor. The role of unavailable carbohydrate remains to be accounted for.
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Review Meta Analysis
Glycemic response and health--a systematic review and meta-analysis: relations between dietary glycemic properties and health outcomes.
Reduction of dietary glycemic response has been proposed as a means of reducing the risk of diabetes and coronary heart disease. The impact of glycemic response on markers of health remains to be elucidated. ⋯ Consumption of reduced glycemic response diets are followed by favorable changes in the health markers examined. The case for the use of such diets looks compelling. Unavailable carbohydrate intake is equally important.
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Interest in the glycemic impact of diet on health and well-being is growing among health care professionals and consumers. Diets with high glycemic impact have been postulated to increase risk of obesity, insulin resistance, diabetes, and cardiovascular disease. A reduction in the glycemic impact of the diet has been proposed as a means of assisting body weight management, improving blood glucose control, and reducing diabetic, cardiovascular, and related risks. ⋯ Yet, a scientific debate exists about whether a relation between the glycemic response to diet and health truly exists, and, if so, which descriptor of a food's glycemic properties best predicts its effect on health outcomes. This article reports the proceedings of a workshop at which a meta-analysis of the relation between the glycemic response to foods and health was presented and the merits of glycemic index (GI), glycemic load (GL), and glycemic glucose equivalent as predictors of health outcomes were discussed. The conclusions include the findings that many studies purporting to investigate lower GI interventions actually studied lower GL interventions; that unavailable carbohydrate (eg, dietary fiber), independent of GI, seems to have at least as big an effect on health outcome as GI itself; that lower GI and GL diets are beneficial for health in persons with impaired glucose metabolism, but that it is as yet unclear what they mean for healthy persons; and that the larger the divergence of glucose metabolism from the norm, the larger the effect of lower GI and GL interventions.
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Review
Role of glycemic index and glycemic load in the healthy state, in prediabetes, and in diabetes.
The choice of carbohydrate-rich foods in the habitual diet should take into account not only their chemical composition but also their ability to influence postprandial glycemia (glycemic index). Fiber-rich foods generally have a low glycemic index (GI), although not all foods with a low GI necessarily have high fiber content. Several beneficial effects of low-GI, high-fiber diets have been shown, including lower postprandial glucose and insulin responses, an improved lipid profile, and, possibly, reduced insulin resistance. ⋯ In relation to prevention of cardiovascular disease, intervention studies evaluating the effect of a low-GI diet on clinical events are not available; moreover, the results of the few available intervention studies evaluating the effects of GI on the cardiovascular disease risk factor profile are not always concordant. The best evidence of the clinical usefulness of GI is available in diabetic patients in whom low-GI foods have consistently shown beneficial effects on blood glucose control in both the short-term and the long-term. In these patients, low-GI foods are suitable as carbohydrate-rich choices, provided other attributes of the foods are appropriate.
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Islet dysfunction and peripheral insulin resistance are both present in type 2 diabetes and are both necessary for the development of hyperglycemia. In both type 1 and type 2 diabetes, large, prospective clinical studies have shown a strong relation between time-averaged mean values of glycemia, measured as glycated hemoglobin (HbA1c), and vascular diabetic complications. These studies are the basis for the American Diabetes Association's current recommended treatment goal that HbA1c should be <7%. ⋯ Interventional studies indicate that reducing postmeal glucose excursions is as important as controlling fasting plasma glucose in persons with diabetes and impaired glucose tolerance. Evidence exists for a causal relation between postmeal glucose increases and microvascular and macrovascular outcomes; therefore, it is not surprising that treatment with different compounds that have specific effects on postprandial glucose regulation is accompanied by a significant improvement of many pathways supposed to be involved in diabetic complications, including oxidative stress, endothelial dysfunction, inflammation, and nuclear factor-kappaB activation. The goal of therapy should be to achieve glycemic status as near to normal as safely possible in all 3 components of glycemic control: HbA1c, fasting glucose, and postmeal glucose peak.