Insulin secretory function in type 2 diabetes: Does it matter how you measure it?

Area of Science:

• Endocrinology
• Metabolic Diseases
• Diabetes Research

Background:

• Widely used methods like HOMA-β, AIRg, and ΔI/ΔG assess pancreatic beta-cell function in type 2 diabetes (2DM).
• These methods have supported the view that 2DM progresses with increasing hyperglycemia due to declining beta-cell function.
• This perspective suggests a direct correlation between hyperglycemia severity and beta-cell impairment.

Purpose of the Study:

• To critically evaluate the physiological validity of current estimates of insulin secretory function.
• To present experimental data challenging the established understanding of beta-cell function in 2DM.
• To question the inevitability of beta-cell function decline in the natural history of type 2 diabetes.

Main Methods:

• Theoretical review of existing insulin secretory function estimates (HOMA-β, AIRg, ΔI/ΔG).
• Analysis of experimental data using hourly plasma insulin and glucose measurements over 8-hour mixed-meal tests.
• Review of studies examining changes in insulin secretory function over time.

Main Results:

• The study raises theoretical questions about the physiological accuracy of common beta-cell function assessments.
• Data from mixed-meal tolerance tests suggest a different perspective on beta-cell function dynamics.
• Evidence reviewed challenges the notion that beta-cell function decline in 2DM is an irreversible, progressive process.

Conclusions:

• Current conventional wisdom regarding the role of beta-cells in type 2 diabetes pathogenesis may need re-evaluation.
• The physiological validity of established methods for estimating beta-cell function requires further scrutiny.
• The natural history of type 2 diabetes may not be characterized by an inexorable decline in beta-cell function as widely assumed.