Insulin Sensitivity And Pancreatic Beta-Cell Function In Patients With Primary Aldosteronism

Background Primary aldosteronism (PA) is associated with an increased risk for dysglycemia. However, the effects of hyperaldosteronism on insulin sensitivity and beta-cell function are unclear.Methods Using a cross-sectional study design, we assessed insulin sensitivity and pancreatic beta-cell function from an oral glucose tolerance test (OGTT) in patients from two cohorts: subjects with PA (n = 21) and essential hypertension control (EHC) subjects (n = 22). Age, sex, BMI, and mean arterial pressure adjusted measures of insulin sensitivity and beta-cell function were compared between the groups.Results PA individuals were less insulin sensitive compared to EHC subjects (Quantitative insulin sensitivity check index [QUICKI]: 0.340 +/- 0.006 vs. 0.374 +/- 0.013, p < 0.001; Matsuda index: 4.14 +/- 0.49 vs. 7.87 +/- 1.42, p < 0.001; S-I: 11.45 +/- 4.85 vs. 21.23 +/- 6.11 dL/kg/min per mu U/mL, p = 0.02). The hepatic insulin resistance index (HIRI) was higher in PA subjects (PA: 5.61 +/- 1.01 vs. EHC: 4.13 +/- 0.61, p = 0.002). The insulinogenic index (IGI), an index of beta-cell function was higher in the PA cohort (PA: 1.49 +/- 0.27 vs. 1.11 +/- 0.21 mu U/mL/mg/dL, p = 0.03). However, the oral disposition index (DI) was similar between the groups (PA: 4.77 +/- 0.73 vs. EHC: 5.46 +/- 0.85, p = 0.42), which likely accounts for the similar glucose tolerance between the two cohorts, despite lower sensitivity.Conclusions In summary, insulin sensitivity is significantly lower in PA with an appropriately compensated beta-cell function. These results suggest that excess aldosterone and/or other steroids in the context of PA may negatively affect insulin action without adversely impacting beta-cell function.