Optimizing Insulin Sensitivity Assessment Using the Minimal Model in Chronic Heart Failure

Abstract

Background: Minimal model analysis of the intravenous glucose tolerance test (IVGTT) has been used successfully to demonstrate that patients with chronic heart failure (CHF) are insulin-resistant. Continuing experience in minimal model methodology has raised questions about how best to assign basal glucose concentrations during such analyses. Methods and Results: IVGTT data from randomly selected patients with CHF (n = 15) and controls (n = 15) were analysed using the minimal model, with the basal glucose concentration (G_b) assigned the value of fasting plasma glucose concentration (G_fast), or the value of plasma glucose concentration 180 minutes after the start of the IVGTT (G₁₈₀). Insulin sensitivity (S_I) was significantly higher with G_b = G_fast, than with G_b = G₁₈₀ (controls: 5.60 ± 0.78 vs. 3.36 ± 0.25/min/μU/ml x 10⁴, p = 0.0017; patients 4.19 ± 0.54 vs. 2.36 ± 0.15/min/μU/ml x 10⁴, p = 0.0004). At G_b = G_fast, CHF patients showed a non-significant 25 % reduction in S_I in comparison to controls (p = 0.15). In contrast, at G_b = G₁₈₀, CHF patients showed a significant 30 % reduction of S_I in comparison to controls (p = 0.0018). S_I estimates derived at G_b = G_fast exhibited twice the variability of those estimated using G_b = G₁₈₀ (coefficients of variation of S_I in patients with CHF were 50.0 % and 24.8 %, respectively). Conclusion: In studies of patients with CHF, greater precision and discriminatory power of insulin sensitivity estimates is obtained when the basal glucose concentration is taken as the plasma glucose concentration 180 minutes after the start of the IVGTT.

Key words

Insulin sensitivity - Minimal model - Chronic heart failure

References

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