Objective: To determine whether adults diagnosed with type 2 diabetes from age 18 to 44 years more aggressively develop clinical complications after diagnosis than adults diagnosed at >or=45 years of age.

Research design and methods: We compared outcomes among 7844 adults in a health maintenance organization who were newly diagnosed with type 2 diabetes between 1996 and 1998. We abstracted clinical data from electronic medical, laboratory, and pharmacy records. To adjust for length of follow-up and sex, we used proportional hazards models to compare incident complication rates through 2001 between onset groups (mean follow-up 3.9 years). To adjust for the increasing prevalence of macrovascular disease with advancing age, onset groups were matched by age and sex to control subjects without diabetes for macrovascular outcomes.

Results: Adults with early-onset type 2 diabetes were 80% more likely to begin insulin therapy than those with usual-onset type 2 diabetes (hazards ratio [HR] 1.8, 95% CI 1.5-2.0), despite a similar average time to requiring insulin ( approximately 2.2 years). Although the combined risk of microvascular complications did not differ overall, microalbuminuria was more likely in early-onset type 2 diabetes than usual-onset type 2 diabetes (HR 1.2, 95% CI 1.1-1.4). The hazard of any macrovascular complication in early-onset type 2 diabetic patients compared with control subjects was twice as high in usual-onset type 2 diabetic patients compared with control subjects (HR 7.9 vs. 3.8, respectively). Myocardial infarction (MI) was the most common macrovascular complication, and the hazard of developing an MI in early-onset type 2 diabetic patients was 14-fold higher than in control subjects (HR 14.0, 95% CI 6.2-31.4). In contrast, adults with usual-onset type 2 diabetes had less than four times the risk of developing an MI compared with control subjects (HR 3.7, P < 0.001).

Conclusions: Early-onset type 2 diabetes appears to be a more aggressive disease from a cardiovascular standpoint. Although the absolute rate of cardiovascular disease (CVD) is higher in older adults, young adults with early-onset type 2 diabetes have a much higher risk of CVD relative to age-matched control subjects.