INS and diabetes mellitus: The HOMA2 - IR in lean DM was lower than in obese DM but significantly higher than in lean controls and mirrored the resistance seen in the obese non-DM group (p < 0.001).<h4>Conclusion</h4>Lean young-onset diabetes in Bangladesh appears to be a phenotype of disproportionate insulin secretory defect with only modest insulin resistance and metabolic dysfunction.