Diabetes mellitus type II-NIDDM--is characterized by insulin insufficiency and insulin resistance. The main therapeutic aim is to mitigate symptoms, achieve and maintain desirable body weight, achieve a normal blood sugar level and treat complications. The main principle of NIDDM therapy remains an adequate dietary programme with reduction of the total energy intake. The greatest problem of successful therapy remains dietary non-compliance of the patient. Oral antidiabetics--in particular sulphonyl urea, have been the basis of therapy for more than 30 years. But even on this point there are some controversial views. The author discusses some problems of the pharmacodynamics and pharmacokinetics of SU, clinical effectiveness, reasons for primary and secondary failure and presents a list of sulphonyl urea derivatives of the second generation.