Large differences in serum leptin levels between nonwesternized and westernized populations: the Kitava study

Objectives. To compare serum leptin between non-westernized and westernized populations. Setting, (i) The tropical island of Kitava, Trobriand Islands, Papua New Gu inea and (ii) the Northern Sweden MONICA study population. Design. Cross-sectional survey. Methods. Fasting levels of serum leptin were analysed in 163 randomly selec ted Kitavans aged 20-86 years and in 224 Swedes aged 25-74. Main outcome measures. Mean and determinants of serum leptin. Results. Geometric mean of serum leptin in Kitavan males and females were 1 .5 and 4.0 vs. 4.9 and 13.8 ng mL(-1) in Swedish male and females (P < 0.00 01 for both sexes). In Kitavans, observed geometric mean were close to pred icted levels (1.8 ng mL(-1) for males and 4.5 ng mL(-1) for females) based on multiple linear regression equations including body mass index (BMI), tr iceps skinfolds (TSF) and age from the Swedish population-based sample. In Kitavans serum leptin was positively related to TSF amongst both sexes and, amongst females, to BMI. In Kitavans leptin was not related to fasting ser um insulin. TSF explained 55% of the variation of leptin amongst females. T here was a slight age-related increase of leptin amongst males. In Kitavans leptin was not related to fasting serum insulin which was substantially lo wer than in Sweden. Conclusion, The low concentrations of serum leptin amongst Kitavans probabl y relates to the absence of overweight and hyperinsulinaemia. At a populati on level serum leptin can apparently be predicted from simple measures of a diposity.