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Updated: May 31, 2026

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Published on: June 25, 2017
A primary defect in glucose production alone cannot induce glucose intolerance without defects in insulin secretion
Salvatore P Mangiafico1, Shueh H Lim, Sandra Neoh
1Department of Medicine, Heidelberg Repatriation Hospital, University of Melbourne, 300 Waterdale Road, Heidelberg Heights, Melbourne, Victoria 3081, Australia.
A primary defect in glucose production alone does not cause glucose intolerance. Insulin resistance and impaired insulin secretion are necessary to precipitate glucose intolerance, even with elevated gluconeogenesis (GNG).
Area of Science:
- Metabolism and Endocrinology
- Type 2 Diabetes Pathophysiology
Background:
- Increased hepatic glucose production is linked to type 2 diabetes and fasting hyperglycemia.
- The direct causal role of elevated gluconeogenesis (GNG) in glucose intolerance remains unclear.
Purpose of the Study:
- To investigate if a primary defect in GNG, leading to increased glucose production, is sufficient to cause glucose intolerance.
- To determine the necessity of insulin resistance and impaired insulin secretion in the development of glucose intolerance.
Main Methods:
- Utilized phosphoenolpyruvate carboxykinase (PEPCK) transgenic rats, a model of primary GNG increase.
- Assessed glucose tolerance, GNG, insulin sensitivity, and insulin secretion using various tolerance tests and hyperinsulinemic/euglycemic clamps.
Main Results:
- PEPCK transgenic rats with elevated GNG showed normal glucose tolerance due to effective glucose disposal and insulin secretion.
- Glucose intolerance manifested only after the development of insulin resistance (hepatic and peripheral) and impaired insulin secretion.
Conclusions:
- A sole genetic defect in GNG does not adversely affect glucose tolerance.
- Insulin resistance and defective glucose-mediated insulin secretion are critical prerequisites for developing glucose intolerance in states of chronic glucose oversupply.
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