INS and Insulin resistance: Table 2 shows the correlations between δ13CO2 (‰) breath test results and variables related to insulin resistance, before and after adjusting for total CO2 production during the test. After adjusting for total CO2 production, δ13CO2 correlations with HOMA and fasting glucose were less strong but remained significant; however, correlations with fasting insulin, waist circumference, BMI, and percent body fat were no longer significant (P > 0.05).