Although there was no significant association between COMT Val108/158Met polymorphism and changes in BMI, body weight, fasting glucose levels and HbA1c, patients with T2DM were additionally subdivided into COMT Val108/158Met A carriers (i.e. subjects carrying the combined AG and AA genotypes) vs. GG homozygotes. The gene discussed is COMT; the disease is type 2 diabetes mellitus.