The disposition index: adjustment for peripheral vs. hepatic insulin sensitivity?

Area of Science:

• Metabolic physiology
• Endocrinology
• Human physiology

Background:

• Assessing human pancreatic beta cell function is challenging due to the interplay of insulin secretion, insulin sensitivity, and hepatic insulin extraction.
• The disposition index approximates the relationship between insulin secretion and sensitivity, assuming a constant product for individuals with similar glucose tolerance.
• Existing debates surround the disposition index's strengths and limitations in reflecting beta cell function.

Purpose of the Study:

• To explore an unrecognized dimension of the disposition index: adjusting insulin secretion for hepatic versus peripheral insulin sensitivity.
• To investigate the differential roles of the liver and muscle in regulating in vivo insulin secretion.
• To provide a comprehensive review of the disposition index in the context of human metabolic health.

Main Methods:

• Literature review focusing on the disposition index and its components.
• Analysis of studies examining hepatic and peripheral insulin sensitivity.
• Discussion of the physiological basis for differential insulin action in the liver and periphery.

Main Results:

• The disposition index is a simplified model with debated strengths and limitations.
• A key consideration is the adjustment of insulin secretion for varying insulin sensitivities.
• The liver and muscle play distinct roles in insulin regulation, impacting the interpretation of the disposition index.

Conclusions:

• The disposition index requires careful interpretation, particularly regarding hepatic versus peripheral insulin sensitivity.
• Understanding the differential roles of liver and muscle in insulin metabolism is crucial for accurate assessment of pancreatic beta cell function.
• Further research is needed to refine models assessing beta cell function in humans.