Glucose and Insulin Metabolism
The postprandial the total glucose response remains unchanged compared to wheat products, but after consuming rye bread the glucose profile seems to be different between these two. Wheat induces a fast and high peak in blood glucose after which the glucose can drop under fasting level, causing a slight hypoglycemia. The acute response to rye bread meal is more moderate and the decent after the peak blood glucose value is slower, usually not leading to values lower than fasting level.
Rye products generate a lower postprandial insulin response than wheat products. This response is not only due to the fiber content of rye, but also due to the bioactive components and the physical structure of rye products, e.g. rye breads. Also, there is evidence that grain variety influences the postprandial insulin metabolism, some varieties showing more insulin saving capacity than others.
Hypothetically, repeated lower postprandial insulinemic responses may allow beta cell function to recover or decrease insulin resistance, which improves early insulin secretion over the long term. In line with this hypothesis, it has been established that high-fiber rye bread increased the acute insulin response, but insulin sensitivity remained unchanged in the long run. Only one large study, in which rye intake was measured with a biomarker, has rye consumption been linked to enhanced insulin sensitivity and lower fasting insulin levels in persons with metabolic syndrome.
Furthermore, it has been shown that rye bread and pasta-based carbohydrate modification can enhance early insulin secretion in persons with the metabolic syndrome, although no changes in glucose tolerance or insulin resistance were observed. It has been recently shown that rye bread and pasta based diet down-regulated genes responsible for insulin signaling suggesting that such carbohydrate modifications may influence the risk of type 2 diabetes.
Several clinical studies support the hypothesis that whole grain consumption and especially high intake of cereal fiber is significantly associated with reduced risk of diabetes.
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