Association between within-target risk factors and life expectancy free from cardiovascular disease, cancer, and dementia in individuals with type 2 diabetes in New Zealand between 1994 and 2018: a multi-ethnic cohort study

Abstract

BackgroundThe extent to which type 2 diabetes (T2D) reduces life expectancy depends on the risk of complications. We aimed to characterise the relationship between risk factors for diabetes complications and life expectancy, in individuals with T2D, free from major chronic disease, in a regional database linked with national New Zealand health databases.MethodsA prospective cohort study design was employed, analysing data from individuals with T2D drawn from the comprehensive Diabetes Care Support Service database (1994–2018). Participants with known values for all five within-target risk factors (WTRF +) including blood pressure, glycaemia, and LDL cholesterol, alongside being non-smoking with normal renal function at baseline, were included. Life expectancy free from cardiovascular disease (CVD), cancer, and dementia at age 50 years was estimated using multistate life tables, adjusting for demographics and clinical metrics.ResultsWomen and men with no WTRF + at enrolment had a life expectancy free from CVD, cancer, or dementia of 13.1 (95% confidence interval: 9.1–19.0) and 11.2 (6.7–18.6) years, respectively. For the most socioeconomically deprived groups or Māori with no WTRF + at baseline, life expectancies were markedly lower. Life expectancies were 23.7 (18.9–29.7) years for women and 23.2 years (17.2–31.4) years for men with four or five WTRF + at baseline, respectively. While an increasing number of WTRF + at baseline was significantly associated with improved outcomes in men and certain subgroups (e.g. Other ethnicity group), this trend was not statistically significant for women overall or in most subgroups.ConclusionsHaving multiple WTRF + at baseline is associated with a considerable increase in life expectancy free from major chronic disease among individuals with T2D. This highlights the importance of lifestyle and clinical interventions in the management of T2D and in the prevention and management of associated chronic conditions.