Lean Metabolic Syndrome: A Concept or a Reality?

AIMS AND OBJECTIVES: Metabolic syndrome (MetS) is fairly common in India. International Diabetes Federation (IDF) has defined it as the presence of central obesity with region/ethnicity-specific waist circumference as a mandatory defining criterion along with the presence of two other features from dysglycemia, systolic and/or diastolic hypertension, hypertriglyceridemia, and low high-density lipoprotein. Although obesity is not prevalent in rural parts of India, especially among the underprivileged population, other individual components of the syndrome are not infrequent among these lean/nonobese persons. In this study, we evaluated the prevalence of MetS in rural West Bengal. We also examined that if those persons above the recommended cutoff for waist are excluded, and thus only lean/nonobese persons are included, and the same definition of MetS (herein termed as lean MetS) is applied (three out of four criteria), what will be the prevalence of MetS and will it be lower in the nontribal population compared to the tribal population? MATERIALS AND METHODS: A population-based study was done in the rural area of West Bengal comprising 200 peoples from scheduled tribe (ST) population and 205 people from the neighborhood community from non-ST population to compare the metabolic health with respect to anthropologic and biochemical parameters. RESULTS: The prevalence of MetS from rural areas of West Bengal was found to be 21.48% as per IDF criterion, but applying NCEP ATP III criteria, the overall prevalence of MetS rose to 31.1%. The prevalence of normal waist/lean MetS was 12.8%, and there was no significant difference between nontribals versus tribal cohort (14.6% of the nontribes versus 11.6% of the tribal cohort, P = 0.436). CONCLUSION: A significant number of persons with nonobese/lean MetS exist in the rural area. We suggest that if region-specific waist criteria are not satisfied, the diagnosis should still be sorted by NCEP ATP III criteria.