Long-term complications and mortality in young-onset diabetes: type 2 diabetes is more hazardous and lethal than type 1 diabetes.

Objective: To evaluate long-term clinical outcomes and survival in young-onset type 2 diabetes (T2DM) compared with type 1 diabetes (T1DM) with a similar age of onset.

Research Design And Methods: Records from the Royal Prince Alfred Hospital Diabetes Clinical Database, established in 1986, were matched with the Australian National Death Index to establish mortality outcomes for all subjects until June 2011. Clinical and mortality outcomes in 354 patients with T2DM, age of onset between 15 and 30 years (T2DM15-30), were compared with T1DM in several ways but primarily with 470 patients with T1DM with a similar age of onset (T1DM15-30) to minimize the confounding effect of age on outcome.

Results: For a median observation period of 21.4 (interquartile range 14-30.7) and 23.4 (15.7-32.4) years for the T2DM and T1DM cohorts, respectively, 71 of 824 patients (8.6%) died. A significant mortality excess was noted in T2DM15-30 (11 vs. 6.8%, P = 0.03), with an increased hazard for death (hazard ratio 2.0 [95% CI 1.2-3.2], P = 0.003). Death for T2DM15-30 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 T2DM15-30 (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 T2DM15-30 cohort, even soon after diabetes onset. Neuropathy scores and macrovascular complications were also increased in T2DM15-30 (P < 0.0001).

Conclusions: Young-onset T2DM is the more lethal phenotype of diabetes and is associated with a greater mortality, more diabetes complications, and unfavorable cardiovascular disease risk factors when compared with T1DM.