Characteristics of an adult population with newly diagnosed type 2 diabetes: the relation of obesity and age of onset.

OBJECTIVE: To determine whether adults diagnosed with type 2 diabetes at 18-44 years of age (early type 2 diabetes) have different metabolic profiles at diagnosis than adults diagnosed at > or =45 years of age (usual type 2 diabetes). RESEARCH DESIGN AND METHODS: Within a health maintenance organization, we studied characteristics among 2,437 adults newly diagnosed with type 2 diabetes between 1996 and 1998 who had measured weight, HbA(1c), blood pressure, and cholesterol within 3 months of diagnosis. We abstracted clinical data from electronic medical records. We compared mean and proportional differences with parametric t tests and chi(2) analyses, respectively. We used multiple logistic regression to identify the factors independently associated with the onset group (early vs. usual type 2 diabetes).
RESULTS: There was an inverse linear relationship between BMI and age at diagnosis of type 2 diabetes (P < 0.001). On univariate analysis, adults with early type 2 diabetes were more obese (BMI 39 vs. 33 kg/m(2), P < 0.001), were more likely to be female (P = 0.04), had slightly worse glycemic control (HbA(1c) 7.7 vs. 7.5%, P = 0.03), had a higher prevalence of diastolic hypertension (37 vs. 26%, P < 0.001), despite a lower prevalence of systolic hypertension (34 vs. 55%, P < 0.001), and had an equally high rate of abnormal lipids (82 vs. 78%, P = 0.13) than adults with usual type 2 diabetes. BMI, female gender, cholesterol, and diastolic and systolic blood pressure remained independently associated with onset group at multivariate analysis.
CONCLUSIONS: Although both onset groups were on average obese, the inverse linear relationship of obesity and age of diabetes onset that we observed suggests that obesity is a continuous risk rather than a threshold risk for diabetes onset. Both onset groups had a high prevalence of cardiovascular disease risk factors.