Objective: Within the frame of a randomized clinical trial to examine whether training of general practitioners (the intervention group) in intensive lifestyle modification and pharmacological treatment of patients with type 2 diabetes has a spillover effect on individuals with impaired fasting glycaemia (IFG) or impaired glucose tolerance (IGT).
Design: A high-risk screening study for type 2 diabetes with an intervention programme, where general practices were randomized to provide standard treatment versus intensive lifestyle modification and pharmacological treatment to newly diagnosed diabetic patients.
Setting: General practices in Denmark.
Subjects: Of 1821 individuals identified with IFG or IGT, results from oral glucose tolerance tests after one and three years were available in 1510 individuals.
Main outcome measures: Progression rates from IFG and IGT to diabetes and effect of intervention were estimated in a regression model using interval censoring.
Results: A total of 442 persons developed diabetes. There was no significant overall effect of intervention on progression rates. For risk factors, no difference in rate of change was found between randomization groups, but a difference was found between general practices within the same randomization groups.
Conclusion: General practitioners identify a high number of incident diabetes cases in individuals with IFG or IGT found by high-risk screening. Intervention at the general practitioner's level in intensive treatment type 2 diabetes does not have a significant spillover effect reducing the risk of diabetes from pre-diabetic conditions. This could indicate that intervention strategies should be specifically targeted at individuals with IFG or IGT, either by training general practitioners or directly at the individual level.