Clinical and mortality outcomes in 354 patients with T2DM, age of onset between 15 and 30 years, were compared with T1DM in several ways but primarily with 470 patients with T1DM with a similar age of onset to minimize the confounding effect of age on outcome. A significant mortality excess was noted in T2DM (11 vs. 6.8%, P = 0.03). Death for T2DM occurred after a significantly shorter disease duration (26.9 [18.1–36.0] vs. 36.5 [24.4–45.4] years, P = 0.01) and at a relatively young age. There were more cardiovascular deaths in T2DM (50 vs. 30%, P < 0.05). Despite equivalent glycemic control and shorter disease duration, the prevalence of albuminuria and less favorable cardiovascular risk factors were greater in the T2DM cohort, even soon after diabetes onset. Neuropathy scores and macrovascular complications were also increased in T2DM (P < 0.0001).

For those with young-onset T2DM, the increased lifetime exposure to hyperglycemia predicts a high complications risk over time. Moreover, there is evidence for an increased inherent susceptibility to complications, namely retinopathy in diabetes presenting earlier rather than later in life . Furthermore, the results from the recent TODAY (Treatment Options for Type 2 Diabetes in Adolescents and Youth) study, which examines optimal treatment regimens in young-onset T2DM, illustrate the difficulty in achieving and maintaining good glycemic control in youth, highlighting the lifelong metabolic challenges of early onset T2DM. Together, these observations predict a poorer prognosis for young-onset T2DM.