Obesity and overweight phenotypes in patients with systemic lupus erythematosus based on body mass index and serum leptin levels: a pilot cross-sectional study

Abstract

Objective – to identify obesity/overweight phenotypes in patients with systemic lupus erythematosus (SLE) based on the body mass index (BMI) and serum leptin levels assessment, and to clarify the relationship of these phenotypes with different metabolic disorders.Material and methods. The study included 51 patients with SLE (48 women, 3 men) without diabetes mellitus. The median age of patients was 40 [31; 48] years, disease duration was 3.0 [0.6; 9.0] years. Glucocorticoids were received by 84% of patients, hydroxychloroquine – by 76%, immunosuppressants – by 20%, biological agents – by 10%. BMI was calculated and the fasting leptin level in serum was determined (ELISA) in all patients. Leptin concentrations >11.1 ng/ml in women and >5.6 ng/ml in men corresponded to hyperleptinaemia. There were three main obesity/overweight phenotypes: “classic” (BMI≥25 kg/m2 + hyperleptinemia), “healthy” (BMI≥25 kg/m2 , without hyperleptinemia), “hidden” or “latent” (BMI<25 kg/m2 + hyperleptinemia), as well as “normal weight” (BMI><25 kg/m2 , without hyperleptinemia).>˂ 25 kg/m2 + hyperleptinemia), as well as “normal weight” (BMI˂ 25 kg/m2 , without hyperleptinemia).Results. The “classic” phenotype of obesity/overweight was diagnosed in 22 (43%) patients, the “healthy” – in 1 (2%), the “hidden” – in 14 (27.5%) patients with SLE. Insulin concentrations were: 10.0 [7.5; 17.9] μU/mL in the “classic” phenotype, 8.3 [6.0; 11.9] μU/mL in the “hidden” phenotype, and 5.3 [4.2; 6.3] μU/ml at “normal weight” (p=0.001). HOMA-IR index were: 2.18 [1.70; 4.23], 1.78 [1.23; 2.41] and 1.18 [0.95; 1.52], respectively (p=0.002). The levels of glucose, total cholesterol, ApoB did not differ in the groups. The uric acid concentrations were the highest in the “classic” phenotype group (334 [365; 388] μmol/l), the lowest in the group of “hidden” obesity/overweight (257 [214; 296] μmol/l), and intermediate in “normal weight” group (286 [236; 377] μmol/l) (p=0.04).Conclusion. The majority of SLE patients hade the “classic” obesity/overweight phenotype, while the “healthy” phenotype was extremely rare. In 27.5% of patients, the presence of a “latent” phenotype was confirmed, which, in terms of metabolic disorders, is an intermediate stage between “normal weight” and “classic” obesity. For rational and timely prevention of insulin resistance, metabolic syndrome and related complications, it is necessary to actively identify the “hidden” phenotype.