Objective: To study trends in body mass index (BMI) at diagnosis of diabetes in all young Swedish adults in the age range of 15-34 years registered in a nation-based registry.
Design: The BMI was assessed at diagnosis in diabetic patients 15-34 years of age at diagnosis, for a period of 17 years (1983-1999). Islet cell antibodies (ICA) were measured during three periods (1987-1988, 1992-1993 and 1998-1999).
Setting: A nationwide study (Diabetes Incidence Study in Sweden).
Subjects: A total of 4727 type 1 and 1083 type 2 diabetic patients.
Main outcome measures: Incidence-year specific BMI adjusted for age, gender and time of diagnosis (month).
Results: Body mass index at diagnosis increased significantly both in type 1 (21.4 +/- 3.6 to 22.5 +/- 4.0; P < 0.0001) and in type 2 (27.4 +/- 6.8 to 32.0 +/- 6.0; P < 0.0001) diabetic patients, also when adjusted for age, gender and month of diagnosis. A similar significant increase in BMI was found in type 1 diabetic patients and in type 2 diabetic patients in the periods 1987-1988, 1992-1993 and 1998-1999; years when ICA were assessed and considered in the classification of diabetes. Despite this increase in BMI, there was no increase in the incidence of diabetes in young-adult people in Sweden.
Conclusion: Body mass index at diagnosis of diabetes in subjects 15-34 years of age has substantially increased during 1983-1999 in Sweden when adjusted for age, gender and month of diagnosis.