OBJECTIVE To describe the rationale and design, and to discuss the preliminary screening data, of the Study to Prevent NIDDM (STOP-NIDDM Trial), an international study on the efficacy of the α-glucosidase inhibitor acarbose in preventing or delaying the development of type 2 diabetes in a population with impaired glucose tolerance (IGT).

RESEARCH DESIGN AND METHODS A total of 1,418 subjects diagnosed with IGT according to the World Health Organization's criteria and having a fasting plasma glucose concentration ≥5.6 mmol/l were randomized in a double-blind fashion to receive either acarbose (100 mg t.i.d.) or placebo for a predictive median follow-up period of 3.9 years. The primary outcome is the development of type 2 diabetes diagnosed using a 75-g oral glucose tolerance test according to the new criteria. The secondary outcomes are changes in blood pressure, lipid profile, insulin sensitivity, cardiovascular events, and morphometric profile.

RESULTS Screening was performed in a high-risk population. As of 1 March 1997, 4,424 subjects had been screened, and data were available for 3,919 (88.5%) subjects. Of these subjects, 1,200 (30.6%) had glucose intolerance. Of the subjects with glucose intolerance, 521 (13.3%) had previously undetected type 2 diabetes, and 679 (17.3%) had IGT. Of the IGT population, 412 (60.7%) subjects were eligible for the study. This population had the following characteristics: the mean age was 54.8 years, 52% of the subjects were female, 53% had more than one risk factor for type 2 diabetes, >90% had a family history of diabetes, 78.2% had a BMI ≥27 kg/m², 47.5% had high blood pressure, 51.2% had dyslipidemia, and 22.8% of the women had a history of gestational diabetes.

CONCLUSIONS Screening of a high-risk population yields one eligible subject per every 10 volunteers screened. This study should definitely answer the question of whether acarbose can prevent or delay the progression of IGT to type 2 diabetes mellitus.