Unrecognized glucose intolerance is common in pulmonary arterial hypertension

Abstract

Background: Animal and human data suggest insulin resistance is common in pulmonary arterial hypertension (PAH). Although routine assessment of insulin resistance is difficult, hemoglobin A(1c) (HbA(1c)) is a sensitive test to detect diabetes mellitus (DM) and those at high risk for DM. We aimed to define the prevalence of elevated HbA(1c) in PAH patients and to correlate HbA(1c) levels with functional assessment.

Methods: HbA(1c) was measured in 41 PAH patients without a diagnosis of DM, along with demographic, functional, and hemodynamic data. Using published criteria, HbA(1c) ≤ 5.9% defined normal, 6.0% to 6.4% was glucose intolerance, and ≥ 6.5% was DM.

Results: Twenty-three patients (56%) had HbA(1c) ≥ 6.0%, and 6 (15%) had unrecognized DM (HbA(1c) ≥ 6.5%). Age and body mass index were similar in patients with HbA(1c) ≥ 6.0% vs < 6.0%. There was a trend towards lower mean 6-minute walk distance in patients with elevated HbA(1c) (331.0 ± 126.6 vs 413.6 ± 74.9 meters, p = 0.07). The 6-month event-free survival was not significantly different in patients with elevated HbA(1c).

Conclusions: Unrecognized glucose intolerance as assessed by HbA(1c) is common in PAH. Further studies are needed to discern if glucose or insulin dysregulation mediates PAH pathogenesis or is secondary to advanced PAH.

Conflict of interest statement

Disclosure Statement

The other authors have no conflicts of interest to disclose.

Copyright © 2011 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1. Distribution of Hemoglobin A1c (HbA1c) values in PAH patients without known history of Diabetes Mellitus (DM)

“No.” represents the number of patients (total = 41) with each value of HbA1c. Arrows highlight HbA1c

Figure 2. BMI is not correlated with HbA1c in PAH

Slope 0.007 (95% CI: −0.017 to 0.03), R2 = 0.01, p = 0.79 using Spearman’s correlation.

Figure 3. Glucose intolerance by WHO Class

HbA1c

Figure 4. Mean six-minute walk distance is lower in patients with elevated hemoglobin A1c (HbA1c)

Dark bar demonstrates mean, grey bars represent 95% CI. *p value = 0.07 by Mann-Whitney U test.

Figure 5. Kaplan-Meier six-month event-free survival curve in pulmonary arterial hypertension (PAH) by HbA1c

There was no significant difference in event free survival in PAH patients with HbA1c