People in the age range 40 ≤ age < 64 (adjusted-HR = 3.36; 95% CI = 3.06–3.70; p for interaction < 0.001), who were heavy-drinkers (adjusted-HR = 3.19; 95% CI = 2.67–3.82; p for interaction = 0.010), those without dyslipidemia (adjusted-HR = 2.50; 95% CI = 2.33–2.68; p for interaction = 0.015), and who were not on insulin therapy (adjusted-HR = 2.49; 95% CI = 2.32–2.67; p for interaction = 0.031) showed a stronger association between being underweight and SCD compared with their counterparts. The gene discussed is INS; the disease is metabolic syndrome.