On the contrary, lower proportion of optimal HbA1c level was associated with current cigarette smoking (aOR = 0.82, 95% CI = 0.75–0.89, compared with non-smoker); the presence of central obesity (aOR = 0.70, 95% CI = 0.64–0.75), dyslipidaemia (aOR = 0.58, 95% CI = 0.50, 0.67), diabetic retinopathy (aOR = 0.71, 95% CI = 0.60–0.85); use of insulin therapy (aOR = 0.33, 95% CI = 0.29–0.37), oral hypoglycemic drugs (aOR = 0.22, 95% CI = 0.19–0.26), and diabetes duration of DM for over 10 years (aOR = 0.62, 95% CI = 0.57–0.67). Here, INS is linked to diabetes mellitus.