All-cause mortality in insulin-treated diabetic patients: a 20-year follow-up

To establish all-cause mortality rates, and risk factors for mortality in insulin-treated diabetic individuals living in Canterbury, New Zealand.

Insulin-treated diabetic subjects (n=995) on the Canterbury Diabetes Registry were followed up over 20-year and vital status determined. Death rates were standardised and hazard regression was used to model the effects of demographic covariates on relative survival time.

Six subjects had emigrated, the remaining 989 diabetic subjects contributed a total of 13705.53 person-years of follow-up, a mean of 13.7 years per subject. During follow-up 525 deaths occurred in subjects' aged 17.3-96.7, (261 females, 264 males). All-cause mortality rates in diabetic subjects exceeded those in the general population at all ages. SMRs were slightly higher for females than males in almost all age-at-onset groups, being 2.48 (95% CI: 2.18-2.78) for females and 2.17 (95% CI: 1.91-2.43) for males overall, but reaching a peak in the <30 age at onset group for both females and males being 4.25 (3.07-5.44) and 3.26 (2.49-4.03), respectively.

Mortality rates for diabetic individuals remain high, resulting in shortened life spans relative to the general population. This study provides a baseline for further studies of mortality and changes in mortality within New Zealand.