Population based randomized controlled trial of screening for type 2 diabetes mellitus in high-risk subjects.

The aim of this study is to establish whether systematic screening for type 2 diabetes mellitus in high-risk obese subjects can significantly reduce the diabetes-related cardiovascular morbidity and mortality among diabetic patients by at least 25%, resulting in a 5% reduction of these endpoints within the entire overweight/obese population. The study will be a population-based RCT in a high-risk group and has a total duration of 10 years. In the first year, feasibility of the project will be assessed in 20% of the intended sample size. Inclusion criteria are age (40-74 years), self-reported waist circumference (>80cm for women and > 94cm for men), long-term follow-up feasible, i.e. no presence of other chronic diseases that makes 5-year survival unlikely and no previous diagnosis of type 1 or type 2 diabetes. After identification of the personal data from municipal registries, 450.000 people will receive an invitation letter, information brochure, questionnaire, tape-measure and consent form. We aim at including 62.000 men and women, to be equally randomized over two study arms. The screening arm will be invited for a fasting plasma glucose (FPG) measurement. Blood lipids and blood pressure in a subset of individuals will additionally be measured to evaluate the ‘overlap’ between these risk factors in the obese population. Participants with ‘diabetes’ or ‘impaired fasting glucose’ will be referred to their GP for further diagnostics and treatment. The control arm will not be invited for a FPG. Both groups will receive written information about beneficial effects of a healthy life style. The primary endpoint is based on the first occurrence, within the follow-up period after randomization, of a fatal or non-fatal cardiovascular event.

Systematic screening for type 2 diabetes in high-risk obese subjects, identified from the general population, can significantly reduce the diabetes-related cardiovascular morbidity and mortality by at least 25% compared with not offering a screening program.

Subjects will be randomized into a screening group and a control group. All subjects who have been allocated to the screening group will be invited for screening which comprises a fasting plasma glucose test (FPG). Additionally, serum triglycerides, total-cholesterol and HDL-cholesterol and LDL-cholesterol will be measured. LDL-cholesterol will be calculated using the Friedewald equation. Those subjects with diabetes (FPG of 7.0 mmol/L or higher) or impaired fasting glucose (FPG between 5.7-6.9 mol/L) will be referred to the general practitioner for further diagnostic testing and/or treatment for type 2 diabetes according to NHG-guidelines. Individuals with normal FPG (5.6 mmol/L or lower) will be invited for re-screening after 4 years. All subjects in both groups will receive written lifestyle intervention advice.