Proton magnetic resonance spectroscopy study of soleus muscle in non-obese healthy and Type 2 diabetic Asian Northern Indian males: high intramyocellular lipid content correlates with excess body fat and abdominal obesity

Abstract

Aims: Intramyocellular lipids (IMCL) appears to be important in the pathogenesis of insulin resistance. Correlation of IMCL content of soleus muscle with insulin sensitivity has been reported in the Caucasian population. In the present study, IMCL content was estimated in the soleus muscle of both non-obese healthy males and Type 2 diabetic males, and correlated with the anthropometric parameters, blood glucose, plasma lipids, and insulin resistance in Asian Indians from North India. Methods: Twenty males (Type 2 diabetes mellitus 10; healthy controls 10) with body mass index (BMI) ≤25 kg/m² were recruited in the study. In both healthy and diabetic groups, five subjects had percentage body fat (%BF) ≤25, and other five subjects had percentage BF> 25. The following were assessed in all subjects: body composition, fasting blood glucose, lipid profile, insulin levels, insulin resistance by homeostasis model assessment, and proton magnetic resonance spectroscopy (¹H MRS) study of the soleus muscle. Results: IMCL content was approximately two times higher in Type 2 diabetic males compared with healthy males (P< 0.05). Amongst healthy males, IMCL content was significantly higher (P< 0.05) in subjects with percentage BF> 25 compared with subjects with percentage BF ≤ 25. Similarly, IMCL content was high in subjects with waist-hip ratio (WHR)> 0.95 compared with subjects with WHR ≤ 0.95. In healthy males but not in diabetic males, positive significant correlation of IMCL content of soleus muscle was observed with waist circumference (r = 0.73, P< 0.05) and WHR (r = 0.71, P< 0.05). However, IMCL content did not correlate significantly to insulin resistance in both the groups. Conclusions: ¹H MRS study of soleus muscle in a small sample of non-obese Asian Indians showed higher IMCL content in Type 2 diabetics compared with healthy subjects. Non-obese healthy male subjects having high percentage BF and WHR also had high IMCL content, and it significantly correlated to waist circumference and WHR. However, lack of relationship of IMCL content with insulin resistance in Asian Indians needs further study.