What is the pathophysiology of glucose intolerance?

Updated: Jul 08, 2020
  • Author: Samuel T Olatunbosun, MD, FACP, FACE; Chief Editor: George T Griffing, MD  more...
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Answer

Glucose intolerance may be present in many patients with cirrhosis due to decreased hepatic glucose uptake and glycogen synthesis. Other underlying mechanisms include hepatic and peripheral resistance to insulin and serum hormonal abnormalities. Abnormal glucose homeostasis may also occur in uremia, as a result of increased peripheral resistance to the action of insulin.

The gastrointestinal tract plays a significant role in glucose tolerance. [18] With food ingestion, incretin hormones glucagonlike peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are synthesized and secreted by specialized gut cells. Oral glucose administration results in a higher insulin secretory response than does intravenous glucose administration; this difference is due in part to incretin hormones.

The significance of incretin hormones has been noted as a result of efforts to develop agents that may improve glycemic control in patients with type 2 diabetes through new mechanisms. [19] These strategies include inhibition of dipeptidyl peptidase IV (DPP-4), the major enzyme responsible for degrading incretin hormones in vivo, and the use of GLP-1 agonists. [20] Incretin hormones also significantly affect the differentiation, mitogenesis, and survival of beta cells.

Pathologic defects observed in type 2 diabetes mellitus and sometimes in impaired glucose tolerance include postprandial hyperglucagonemia, dysregulation of gastric emptying, and loss of incretin effect.

Postprandial hyperglycemia in diabetes and impaired glucose tolerance (IGT) is related to a lower rate of glucose disposal, whereas insulin secretion and action, as well as postprandial turnover, are essentially normal in individuals with isolated IGT. [21]


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