Plasma leptin tied to sleep quality in obese T2DM patients
In obese patients with type 2 diabetes mellitus (T2DM), higher plasma levels of leptin appear to be associated with better sleep quality, a recent study has shown.
Researchers performed a cross-sectional study of 182 T2DM patients, of whom 113 had body mass index (BMI) ≥25 kg/m2 and were identified as obese. Single-channel electroencephalography was used to assess sleep architecture, while enzyme-linked immunosorbent assays were performed to measure fasting plasma leptin concentrations.
The median plasma leptin concentration in the study cohort was 6.6 ng/mL. In the obesity group, the median concentration was 9.9 ng/L, which was significantly higher than the 3.6 ng/mL in the nonobesity group. The median apnoea-hypopnoea index (AHI) value in the obesity group was likewise significantly higher than in the nonobesity group (13.9/hour vs 5.8/hour).
In multiple regression analysis, leptin levels were positively associated with delta power in the entire cohort (β, 0.226; p=0.075) with borderline significance. Age (β, –0.490; p<0.01) and BMI (β, –0.238; p<0.05) were also significantly associated with delta power. The models were adjusted for age, BMI, sex, blood pressure, AHI and leptin levels.
When analyses were restricted to either obese or nonobese participants, researchers found that leptin levels had a significant, strong and positive correlation with delta power among obese (β, 0.399; p<0.01) but not nonobese T2DM patients.
“The present study demonstrated that plasma leptin level was positively associated with delta power during the first sleep cycle, an established marker for sleep quality, only in obese T2DM patients, but not in nonobese counterparts,” noted researchers.