Serum leptin concentration, obesity, and insulin resistance in Western Samoans: cross sectional study
BMJ 1996; 313 doi: https://doi.org/10.1136/bmj.313.7063.965 (Published 19 October 1996) Cite this as: BMJ 1996;313:965
- Paul Zimmet, directora,
- Allison Hodge, senior research officera,
- Margery Nicolson, senior research scientistb,
- Myrlene Staten, director of clinical researchb,
- Maximilian de Courten, senior epidemiologista,
- Jason Moore, research associateb,
- Andrew Morawiecki, research associateb,
- John Lubina, manager of biostatisticsb,
- Gregory Collierc,
- George Alberti, dean of medicinec,
- Gary Dowse, senior epidemiologista
- a International Diabetes Institute, Caulfield 3162, Victoria, Australia,
- b Amgen, 1840 DeHavilland Drive, Thousand Oaks, CA 91320–1789, USA,
- c University of Newcastle upon Tyne, Newcastle upon Tyne NE2 4HH
- Deakin University, Geelong 3220, Victoria, AustrU. Correspondence to: Professor Zimmet.
- Accepted 30 August 1996
Abstract
Objective: To measure serum leptin concentrations in the Polynesian population of Western Samoa and to examine epidemiological associations of leptin with anthropometric, demographic, behavioural, and metabolic factors in this population with a high prevalence of obesity and non-insulin dependent diabetes mellitus.
Design: Cross sectional study, leptin concentration being measured in a subgroup of a population based sample.
Subjects: 240 Polynesian men and women aged 28–74 years were selected to cover the full range of age, body mass index, and glucose tolerance.
Main outcome measurements: Serum leptin, insulin, and glucose concentrations; anthropometric measures; physical activity; and area of residence.
Results: Leptin concentrations were correlated with body mass index (r = 0.80 in men, 0.79 in women) and waist circumference (r = 0.82 in men, 0.78 in women) but less so with waist to hip ratio. At any body mass index, leptin concentration was higher in women than men (geometric mean adjusted for body mass index 15.3 v 3.6 pg/1, P<0.001). Leptin concentration also correlated with fasting insulin concentration (r = 0.63 in men, 0.64 in women) and insulin concentration 2 hours after a glucose load (r = 0.58 in men, 0.52 in women). These associations remained significant after controlling for body mass index; effects of physical activity and of rural or urban living on leptin concentration were eliminated after adjusting for obesity, except values remained high in urban men. 78% of variance in leptin was explained by a model including fasting insulin concentration, sex, body mass index, and a body mass index by sex interaction term. Similar results were obtained if waist circumference replaced body mass index.
Conclusions: The strong relation of leptin with obesity is consistent with leptin production being proportional to mass of adipose tissue. The relation with insulin independent of body mass index suggests a possible role for leptin in insulin resistance or hyperinsulinaemia.
Key messages
They were also strongly correlated with serum insulin concentrations even after adjusting for obesity in both sexes
Concentrations were higher in women than men, even at the same body mass index or waist circumference
Resistance to the effects of leptin may be important in human obesity
Leptin may simply reflect the size of adipose tissue stores, but the independent association with insulin concentration suggests a possible role in insulin resistance or hyperinsulinaemia
Footnotes
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Funding This study was a collaborative project between the government and health department of Western Samoa and the International Diabetes Institute, Melbourne, Australia, with help from the World Health Organization, Western Pacific Region. The work was supported by grant DK-25446 from the National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, USA.
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Conflict of interest MN, MS, JM, AM, JL are full time employees of Amgen, which conducts research on and manufactures leptin.
- Accepted 30 August 1996