The prevalence of diabetes mellitus, primarily Type 2 diabetes, is highest in older persons. However, the natural history of diabetes complications in this age group is unclear and optimal targets for glycemic control remain under debate. We assessed whether older men recently diagnosed with diabetes mellitus have a different prognosis compared to men diagnosed earlier in life.
Design and participants
We conducted a longitudinal cohort study of 11,726 community-dwelling men aged 65 years or more resident in Perth, Western Australia. Of these men 1,433 (12.2%) had diabetes mellitus at baseline (1996-99) and 1,067 were diagnosed with diabetes mellitus during follow-up (until 2010).
Main outcome measures
Hazard ratios for all-cause and cardiovascular disease (CVD)-related mortality were analysed, stratifying for age at diagnosis of diabetes and for diabetes duration.
Men were followed for (mean±SD) 10.6±3.8 years giving 124,016 person-years of follow-up. In multivariate analysis adjusting for age and for conventional cardiovascular risk factors, diabetes at baseline was associated with all-cause (hazard ratio, HR=1.45, 95% confidence interval, CI=1.34-1.57, p<0.001), and CVD-related mortality (HR=1.43, 95% CI=1.18-1.54, p<0.001). Men who were diagnosed with diabetes during follow-up (incident cases) had a higher hazard ratio for all-cause mortality compared to men of similar age diagnosed earlier (HR=1.84, 95% CI=1.67-2.02, p<0.001 vs HR=1.54, 95% CI=1.43-1.66, p<0.001). In the adjusted analyses, for different ages at onset, shorter duration of diabetes was associated with increased mortality risk.
Men diagnosed with diabetes after the age of 65 had higher mortality risk in the years immediately following this diagnosis. The onset of diabetes mellitus later in life is a marker of poorer prognosis and further research is needed to clarify the implications for glycemic therapy in this expanding demographic group.