Type 2 diabetes is also associated with an increase in glucagon secretion, which is frequently forgotten, but which has
important consequences on hepatic glucose production both in the postabsorptive and the postprandial states. Insulin resistance is characterized by an overproduction of glucose by the liver and a reduction of glucose utilization by skeletal muscle. Insulin resistance results from a defect in insulin signalling pathway in target tissues, secondarily to a dysfunction of adipose tissue. Type 2 diabetes never occurs as long as pancreatic β-cells are able to compensate for insulin resistance by an oversecretion of insulin (prediabetic state). The passage from prediabetic state to patent type 2 diabetes is characterized by three major changes. The first one is a reduction of pancreatic β-cells and of compensatory insulin secretion. It is not known whether if this functional defect in β-cells is genetically programmed and/or acquired (glucotoxicity and/or lipotoxicity). This transition is crucial in the natural history of type 2 diabetes. The second one is an overproduction of glucose by the liver, probably secondarily to the oversecretion of glucagon, to an excessive release of free fatty acids and adipocytokines by the adipose tissue. The third one is an increase of insulin resistance in
skeletal muscles, frequently linked to the presence of obesity and an excessive release of free fatty acids and adipocytokines. The aim of the present chapter is to summarize the knowledge of biochemical mechanisms responsible for the anomalies of pancreatic hormone secretion and of insulin action and to try to identify the cellular steps, which should be the basis for a pharmacological approach for the treatment of type 2 diabetes
Type 2 diabetes is also associated with an increase in glucagon secretion, which is frequently forgotten, but which has
important consequences on hepatic glucose production both in the postabsorptive and the postprandial states. Insulin resistance is characterized by an overproduction of glucose by the liver and a reduction of glucose utilization by skeletal muscle. Insulin resistance results from a defect in insulin signalling pathway in target tissues, secondarily to a dysfunction of adipose tissue. Type 2 diabetes never occurs as long as pancreatic β-cells are able to compensate for insulin resistance by an oversecretion of insulin (prediabetic state). The passage from prediabetic state to patent type 2 diabetes is characterized by three major changes. The first one is a reduction of pancreatic β-cells and of compensatory insulin secretion. It is not known whether if this functional defect in β-cells is genetically programmed and/or acquired (glucotoxicity and/or lipotoxicity). This transition is crucial in the natural history of type 2 diabetes. The second one is an overproduction of glucose by the liver, probably secondarily to the oversecretion of glucagon, to an excessive release of free fatty acids and adipocytokines by the adipose tissue. The third one is an increase of insulin resistance in
skeletal muscles, frequently linked to the presence of obesity and an excessive release of free fatty acids and adipocytokines. The aim of the present chapter is to summarize the knowledge of biochemical mechanisms responsible for the anomalies of pancreatic hormone secretion and of insulin action and to try to identify the cellular steps, which should be the basis for a pharmacological approach for the treatment of type 2 diabetes
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