Effect of Liraglutide in Different Abdominal Fat Layers Measured by Ultrasound: The Importance of Perirenal Fat Reduction

Abstract

Introduction: Ultrasonography (US) in patients with obesity allows us to measure different layers of abdominal fat (superficial subcutaneous, deep subcutaneous, preperitoneal, omental, and perirenal), not assessable by DEXA or CT scan. Omental and perirenal fat depots are considered predictors of metabolic complications. Liraglutide is particularly effective in reducing weight in patients with insulin-resistance, but its direct impact on each abdominal fat layer is unknown. Methods: We measured, at the L4 level, all 5 abdominal fat depots in 860 patients with obesity (72.8% women, mean age 56.6 ± 1.5 years, BMI 34.4 ± 4.7 kg/m2, body fat 47 ± 2%, abdominal circumference 105.8 ± 3 cm), before and after 6 months of liraglutide treatment. Laboratory tests for glucose, insulin, and lipid profile were routinely done. T-student was used to compare intraindividual differences. Results: Weight loss was 7.5 ± 2.8 kg (7.96% from baseline), with no differences by sex/age/BMI. Greater loss was observed in patients with higher dosages and NAFLD. All US-measured fat layers showed a significant reduction (p < 0.05) at 6th months. Preperitoneal fat showed a −26 ± 5.5% reduction and 46% of the patients went below metabolic syndrome (MS) risk cut-off values. Omental fat was reduced by −17.8 ± 5% (67% of the patients below MS risk) and perirenal fat by −22.4 ± 4.4% (56% of the patients below MS). Both omental and perirenal fat reduction correlated with total and LDL cholesterol. Higher perirenal fat reduction (−28%) was seen among patients with obesity and hypertension. Perirenal fat also correlated with blood pressure reduction. Conclusion: Liraglutide induces greater fat loss in the layers involved with MS. However, the maximal reduction is seen at perirenal fat, which has been recently related with hypertension and could play an important role in modulating kidney’s expansion and intraglomerular pressure. US is a reproducible clinical tool to assess pathologic fat depots in patients living with obesity.