Aim. To comparatively analyze thyroid abnormalities in patients with type 2 diabetes mellitus (DM2) in the past 10 years. Subjects and methods. The thyroid state 10 years ago and presently was evaluated in 166 and 101 patient with DM2, respectively. The patients underwent in-depth physical examination and thyroid hormone functions were evaluated. Results. The pattern of thyroid disease has changed in the patients with DM2 over a 10-year period. During recent mass and individual iodine deficiency prophylaxis, iodine-deficiency goiter had become substantially less frequent in DM2; the T3/T4 ratio has normalized. The prevalence of nodular goiter has remained unchanged. However, the incidence of autoimmune thyroiditis and hypothyroidism, the subclinical form of the latter in particular, has increased statistically significantly. Hypothyroidism has occurred more often during treatment with glucose-lowering sulfanilamides than during metformin treatment or combined glucose-lowering therapy. Hypothyroidism was generally recognized untimely in the examinees, in elderly patients in particular: the clinical signs of thyroid disease were regarded as manifestations of DM2. Our preliminary data support other authors' opinion that thyroid insufficiency accelerates the rate of development and progression of vascular complications of DM2. The contrinsular effect of Levothyroxine was not recorded during replacement therapy for thyroid insufficiency. Conclusion. Although the incidence of thyroid abnormality is increasing in patients with DM2 in the world, its causes are yet to be explained. The diagnosis of hypothyroidism in patients with DM2 is commonly untimely. At a follow-up of patients with DM2, it is necessary to systematically monitor thyroid function and to initiate levothyroxine replacement therapy in proper time.