A 12-year follow-up study of all-cause and cardiovascular mortality among 10,532 people newly diagnosed with Type 2 diabetes in Tayside, Scotland.

AIMS: To determine absolute and relative risks of all-cause and cardiovascular mortality among patients newly diagnosed with Type 2 diabetes. METHODS: In an observational cohort study using record-linkage databases, based in Tayside, Scotland, UK, we identified newly diagnosed patients with Type 2 diabetes in 1993-2004. We also identified a set of non-diabetic comparators from lists of patients registered with a general practice, individually matched to the diabetic patients by sex, age and deprivation. We followed up patients for mortality and cardiovascular mortality over a 12-year period and calculated hazard ratios using Cox regression. RESULTS: There were 10,532 patients with Type 2 diabetes and 21,056 non-diabetic comparators. Diabetic patients in every age/sex group had higher absolute mortality rates. Even taking deprivation into account, the hazard ratio for mortality was 1.32 (95% CI 1.25-1.40), decreasing to 1.15 (1.09-1.22) after adjusting for pre-existing cardiovascular disease. The hazard ratios for cardiovascular mortality were higher, decreasing from 1.51 (1.37-1.67) to 1.23 (1.11-1.36) after adjusting for pre-existing cardiovascular disease. The hazard ratios decreased with increasing age at diagnosis, although the difference in absolute rate of mortality increased slightly with age. Increased mortality risks were only evident 2 years after diagnosis and increased thereafter. CONCLUSIONS: Patients with Type 2 diabetes have an increased risk of all-cause and cardiovascular mortality compared with non-diabetic comparators, although this is not observable immediately after diagnosis. Age at diagnosis and duration of the disease independently affect absolute and relative mortality risk.

Reporting of diabetes on death certificates of 1872 people with type 2 diabetes in Tayside, Scotland.

BACKGROUND: It has been suggested that diabetes is under-recorded on death certificates. METHODS: We examined the death certificates of 1,872 people with type 2 diabetes in Tayside, Scotland, to determine how frequently diabetes was recorded. RESULTS: Diabetes was mentioned on the certificates of 42.8% and was the underlying cause of death for 6.4%. There was mention of diabetes for 51.3% of the 811 people for whom cardiovascular disease was the underlying cause of death. Being male was associated with less frequent mention of diabetes, with more frequent mention associated with increasing duration of diabetes, increasing age and underlying cardiovascular cause of death. CONCLUSIONS: This study highlights the limitations of using routine mortality data for monitoring the burden of diabetes in populations.

Increasing prevalence of type 2 diabetes in a Scottish population: effect of increasing incidence or decreasing mortality?

AIMS/HYPOTHESIS: We examined incidence, prevalence and mortality from type 2 diabetes mellitus in a Scottish population over 12 years, and evaluated the effects on prevalence of increasing incidence and decreasing mortality. MATERIALS AND METHODS: We used a diabetes clinical information system in Tayside (population 387,908), Scotland, to identify new cases of type 2 diabetes between 1993 and 2004 and to calculate incidence rates and mid-year prevalence. We defined mortality rates as the number of deaths of diabetic people divided by mid-year prevalence. We used logistic and Poisson regression to analyse trends. We then modelled the increase in prevalence for each year for three scenarios, based on whether mortality or incidence rates remained unchanged from 1993. RESULTS: There was a doubling in incidence and prevalence of type 2 diabetes in Tayside over the 12 years, with statistically significant increasing trends of 6.3 and 6.7% per year respectively. The mortality rate decreased. If incidence and mortality had remained at 1993 levels, there would have been an increase in prevalence of 855 per 100,000 in 2003, accounting for 60.1% of the actual increase of 1,423 per 100,000. If there had been no mortality decrease, prevalence in 2003 would have been very similar to the actual prevalence observed. CONCLUSIONS/INTERPRETATION: Decreasing mortality rates in Tayside had less effect on the increase in prevalence than did increasing incidence. Even if incidence and mortality remain unchanged, prevalence will increase by over 20% in the next decade.