Plasma leptin in non-diabetic Asian Indians: association with abdominal adiposity

Plasma leptin concentrations were measured in 144 non-diabetic men and women (age 21-73 years, BMI 14.8-37.7 kg m(-2)), in fasting samples collected during a population survey for diabetes mellitus. Leptin, fasting and 2-h post-glucose load plasma concentrations of glucose and immunoreactive insulin were measured. In a subset of 50 normoglycaemic individuals, subcutaneous fat (SF) and visceral fat (VF) areas at L4-L5 level were also measured by CT. As in other populations, women had significantly higher plasma leptin concentrations than men (p < 0.001) but the values were similar in normal (NGT) and impaired glucose tolerance (IGT). Geometric mean concentrations of leptin in men and women with NGT were 4.8 and 17.7 ng ml(-1), respectively, and the corresponding values in IGT were 6.2 and 19.0 ng ml(-1). Multiple regression analysis in the total group showed that the leptin concentration (log-transformed) was strongly dependent on sex (R2 = 53.4%), BMI (R2 = 17.4%), and to a lesser degree on the 2-h plasma insulin (R2 = 2.4%) and the WHR (R2 = 0.8%). In men, the total abdominal fat showed a strong association with leptin (R2 = 49.3%) and in women the subcutaneous fat area showed a similar effect (R2 = 39.5%). It is likely that subcutaneous and not visceral fat may be a determinant of plasma leptin in Asian Indians, and the correlation between leptin and insulin resistance may be less strong than in other ethnic groups.