GLP1 Receptor Agonists Reduce Fluid Intake in Primary Polydipsia

Background Primary polydipsia, characterized by excessive fluid intake, carries the risk of water intoxication and hyponatremia, but treatment options are scarce. Glucagon-like peptide-1 (GLP-1) reduces appetite and food intake. In experimental models, they also play a role in thirst and drinking behavior in. The aim of this trial was to investigate whether GLP-1 receptor agonists reduce fluid intake in patients with primary polydipsia. Methods: In this randomized, double-blind, placebo-controlled, 3-week crossover-trial, 34 patients with primary polydipsia received weekly dulaglutide (Trulicity®) 1.5mg and placebo (0.9% sodium chloride). During the last treatment week, patients attended an 8-hour evaluation visit with free water access. The primary endpoint was total fluid intake during the evaluation visits. The treatment effect was estimated using a linear mixed-effects model. In a subset of 15 patients and matched controls, thirst perception and neuronal activity in response to beverage pictures were assessed by functional MRI. Results Median [IQR] total fluid intake was 2250ml [1600-2600] on dulaglutide versus 2400ml [1850-3400] on placebo. Patients on dulaglutide reduced fluid intake by 490ml [95%-CI -780, -199], p=0.002, corresponding to a relative reduction of 17%. 24-hour urinary output was reduced by -943ml [95%-CI -1473, -413]. Thirst perception in response to beverage pictures was higher in patients with primary polydipsia versus controls and lower on dulaglutide versus placebo, but functional neuronal activity was similar between groups and treatments. Conclusion: GLP-1 receptor agonists reduce fluid intake and thirst perception in patients with primary polydipsia and could therefore be a novel treatment option for these patients.