Objectives: Obesity, type II diabetes, hypertension, and dyslipidemia are major causes of morbidity and mortality throughout the world. Though these disorders often cluster in individuals and families and are collectively known as syndrome X, the basis for this aggregation is not well understood. To further understand the pathogenesis of syndrome X, a comprehensive epidemiological study was undertaken on the Pacific Island of Kosrae, Federated States of Micronesia (FSM).
Methods: The entire adult (>20 years of age) population of Kosrae underwent a clinical evaluation that included a questionnaire that noted the participants' sex, family data including listing of biological parents, siblings, and children, smoking status, village of residence, age and health status. The medical evaluation included: anthropometric measures (weight, height, waist, hip), serum chemistries (leptin, fasting blood sugar (FBS), insulin, total cholesterol (TC), triglycerides (TG), and apolipoproteins B and A-I (apo B and apo A-I) and blood pressure (BP) measurements.
Results: Obesity (BMI >/=35) was found in 24%, diabetes (FBS >/=126 or 2-hour oral glucose tolerance test >/=200) in 12%, hypertension (SBP >/=140 or DBP >/=90) in 17%, and dyslipidemia (TC >/=240 or TG >/=200 or apo B >/=120 or apo A-I </=88) in 20% of the population. Significant covariate effects after multivariate analysis were as follows: sex affected the frequency of all four disorders, parity affected the frequency of dyslipidemia, smoking affected the frequency of obesity and diabetes, village of residence affected the frequency of obesity, hypertension, and dyslipidemia, and age affected the frequency of all four disorders. Factor analysis identified four independent factors that explained 73% of the total variance of the entire data set: factor 1 (weight, waist, leptin, insulin, and TG), factor 2 (TC, TG, apo B, apo A-I, and insulin), factor 3 (systolic and diastolic BP, FBS, waist and weight), and factor 4 (apo A-I, TG, leptin, and weight).
Conclusions: This population-based study on the Island of Kosrae suggests that syndrome X is a composite of 4 independent factors: obesity with diabetes and hypertriglyceridemia, combined hyperlipidemia with diabetes, hypertension with obesity and diabetes, and increased HDL-low TG with thinness and high leptin. Further studies to identify the genetic components of these factors as well as the individual traits are under way.
Copyright 2000 S. Karger AG, Basel.