No Evidence of Association Between Human 24-Hour Urinary Dopamine and Weight, BMI or Glucose Homeostasis in a Retrospective Analysis

Abstract

Background: Dopamine is an essential neurotransmitter involved in motivation and reward. In obesity, altered dopaminergic responses to food may drive excess energy intake, implicating dopamine in the pathophysiology of obesity. Additionally, dopamine may act as an anti-incretin, potentially facilitating the development of type 2 diabetes. Objectives: This retrospective study investigated associations between urinary dopamine, weight, Body Mass Index (BMI), plasma glucose, and hemoglobin A1c (HbA1c). Methods: Twenty-four-hour urinary dopamine concentrations measured with liquid chromatography tandem mass spectrometry between January 2000 and October 2020 were retrieved from the University Hospitals Leuven clinical database. Records with dopamine disruption disorders or medications, psychiatric conditions, prior bariatric surgery, active malignancies, diabetes mellitus other than type 2 diabetes, chronic renal insufficiency, or urinary creatinine concentration outside the reference range were excluded, yielding 178 records. Spearman correlations and multiple linear regression models were performed; statistical significance was set at P < 0.05. Results: Twenty-four-hour urinary dopamine concentrations positively correlated with body weight and negatively with HbA1c, but these correlations became non-significant when corrected for age, sex, and estimated glomerular filtration rate (eGFR). The only remaining significant correlation was between age and twenty-four-hour urinary dopamine (β = -1.2, P = 0.030). Conclusions: No significant correlations were found between twenty-four-hour urinary dopamine and weight, BMI, or glucose homeostasis, potentially due to the absence of dietary control. As dopamine measurements came from a clinical database, generalizability is limited. Prospective dedicated studies are needed to disentangle the role of peripheral dopamine in the pathophysiology of obesity.