Lean Metabolic Syndrome vis-à-vis Obese Metabolic Syndrome: Observations from an Eastern Indian Tertiary Set-up

Abstract

Background: Metabolic syndrome (MetS) in obese is a fairly common entity. However, excluding the waist circumference (WC) criteria, other components of the MetS are also seen in lean or nonobese people. Our study aimed to determine the prevalence of lean MetS among newly diagnosed MetS cases and compare the biochemical parameters and insulin resistance in lean versus overweight/obese MetS. Methods: A cross-sectional, observational study was conducted over 12 months and included adult patients of either sex, newly diagnosed with MetS. Fever cases, infections such as tuberculosis/HIV/chronic infectious disease, chronic inflammatory diseases, those having endocrine causes of obesity such as Cushing syndrome, known cases of ischemic heart disease, and those on antiobesity medications were excluded. Diagnosed MetS patients were categorized as lean or obese based on the standard criteria. A convenient sample of 50 was considered for either group (lean MetS vs. obese MetS). Included patients were investigated for lipid, liver, glycemic, and insulin resistance profiles. Other parameters included serum uric acid, thyroid function, whole abdomen ultrasound, electrocardiography, two-dimensional echocardiography (ECHO), fibroscan, and polysomnography for obstructive sleep apnea (OSA). Results: The prevalence of lean MetS was 9.87%. Variables such as body mass index, WC, low-density lipoprotein, and systolic blood pressure were significantly higher in the obese MetS in comparison to the lean MetS group. Fasting insulin was also significantly higher in the obese MetS compared to lean MetS. Biochemical measures such as aspartate aminotransferase and alanine transferase were significantly higher for the obese MetS, while the change was nonsignificant for other biochemical measures. Except for complications such as polycystic ovary syndrome, acanthoses nigricans, and gallstones which were significantly higher in the obese MetS group, the rest of the complications were similar in both groups. Conclusion: MetS among nonobese or lean subjects differs in certain aspects from those with obesity. As lean MetS is an emerging entity, clinicians must be aware of it to avoid morbidity.