Methods for quantifying insulin resistance in human immunodeficiency virus-positive patients

Area of Science:

• Endocrinology
• Infectious Diseases
• Metabolic Research

Background:

• Insulin resistance is a concern in human immunodeficiency virus (HIV)-infected individuals.
• Indirect indices are commonly used to assess insulin resistance, but their accuracy is questionable.
• Physiologic methods for quantifying insulin-mediated glucose uptake (IMGU) offer a direct assessment.

Purpose of the Study:

• To directly measure IMGU in non-diabetic HIV-positive subjects.
• To compare the validity of various indirect indices of IMGU with direct physiologic measurements.
• To determine the best indirect predictor of insulin action in this population.

Main Methods:

• Directly measured IMGU by determining steady-state plasma glucose (SSPG) concentrations during a 3-hour insulin, glucose, and somatostatin infusion.
• Administered a 75-g oral glucose tolerance test (OGTT) to assess indirect measures of IMGU.
• Correlated SSPG values with indirect measures like total integrated insulin response and HOMA-IR.

Main Results:

• The total integrated insulin response to an OGTT was the indirect measure most closely related to direct SSPG assessments of insulin action (r=0.78, r²=0.61).
• Other indirect measures, including HOMA-IR, showed significant but weaker correlations with SSPG (r=0.43 to 0.61, r²=0.18 to 0.37).
• Indirect measures explained a limited portion of the variability in direct insulin action.

Conclusions:

• Direct measurement of IMGU via SSPG provides a reliable assessment of insulin action in HIV-infected patients.
• The total integrated insulin response during an OGTT is the most reliable indirect measure but should still be used cautiously.
• Other indirect indices have limited ability to predict insulin action variability in this cohort, necessitating careful application.