Higher Blood Urea Nitrogen and Urinary Calcium: New Risk Factors for Diabetes Mellitus in Primary Aldosteronism Patients

Abstract

Purpose: The aim of the study was to investigate the prevalence and risk factors of diabetes mellitus (DM) in primary aldosteronism (PA) patients. Methods: This case-control study enrolled 259 PA patients in West China Hospital, China from January 2016 to January 2019. Patients were divided into three groups: PA group, PA + impaired fasting glucose (IFG)/impaired glucose tolerance (IGT) group and PA + DM group. Clinical characteristics (like age and sex) and laboratory variables (like plasma aldosterone concentration and plasma renin activity) were compared between three groups. Univariate and multivariate logistic regression analyses were performed to determine risk factors for DM in PA patients. The association of random blood glucose with the above-mentioned factors were also investigated by Pearson correlation analyses. Nomogram model was developed to predict the probability of DM in PA patients. Results: 49 (18.9%) patients were diagnosed with DM and 22 (8.5%) with IFG/IGT in 259 PA patients. Apart from older age, male, higher body mass index, higher triglycerides and lower cholesterol, we found that higher blood urea nitrogen (BUN) and higher 24 h urinary calcium (Ca) might be potential new risk factors for dysglycemia. The nomogram model for DM in PA patients had a good predictive accuracy, with the area under the curve of receiver operating characteristic of 0.839 (95% CI 0.784-0.893). Conclusions: PA patients were more likely to have DM compared with general population. Apart from older age, overweight and dyslipidemia, higher BUN and excessive excretion of urinary Ca may also be the new potential risk factors for DM in PA patients.

Keywords: blood urea nitrogen; diabetes mellitus; primary aldosteronism; risk factors; urinary calcium.

Figure 1

Correlation between maximal random blood glucose (RBG) and potential risk factors for diabetes mellitus (DM) in primary aldosteronism (PA) patients. The risk factors including (A) age, (B) body mass index (BMI), (C) triglycerides (TG), (D) high density lipoprotein (HDL), (E) 24 h urinary Calcium, (F) blood urea nitrogen (BUN), (G) serum creatinine (Crea), and (H) estimated glomerular filtration rate (eGFR).

Figure 2

(A) Nomogram for predicting diabetes mellitus in primary aldosteronism patients. In sex, “0” represented female, “1” represented male. (B) The receiver operating characteristic of the model. The upper left point of the curve had the highest sensitivity and specificity at the same time, and the corresponding risk was the suitable cutoff value for predicting the probability of diabetes mellitus in primary aldosteronism patients. (C) Calibration curve of the nomogram. The dashed line was the ideal prediction and the solid line was the bias-corrected predictive performance of the nomogram. The closer the solid line fitted to the dashed line, the better the predictive accuracy of the nomogram was. (D) Decision curve analysis for the radiomics nomogram. The dashed line represented the nomogram. The gray line was the hypothesis that all primary aldosteronism patients had diabetes mellitus. The black line was the hypothesis that no primary aldosteronism patients had diabetes mellitus.