Cardiovascular Disease Improvements Seen Among Individuals With Type 2 Diabetes, Study Shows

The risk of both heart attack and stroke increases 2- to 3-fold among individuals with comorbid diabetes and cardiovascular issues, according to the World Health Organization; however, recent study results from Fremantle in Western Australia show improved odds of both not occurring among individuals with type 2 diabetes (T2D), as well as less of a risk of hospitalization for heart failure (HF) or lower extremity amputation.

Journal of Clinical Endocrinology & Metabolism today published results from FDS1 (n = 1291; years 1993-2001) and FDS2 (n = 1509; years 2008-2016), the 2 phases of the longitudinal observational Fremantle Diabetes Study (FDS) in Australia. Individuals studied had a mean (SD) age of 64.8 (11.5) years and most (50.3%) were male, but FDS2 contained an overall older population whose T2D was diagnosed at a younger age and more intensively managed. The nondiabetes control group, which was matched by age, sex, and zip code in a 1:4 ratio, comprised 5159 in FDS1 and 6036 in FDS2.

To get comparable results, individuals were administered questionnaires, physical exams, and fasting biochemical tests at their baseline visit. FDS2 included additional questionnaires mailed in between visits. Incident rates (IRs) and incident rate differences were the primary outcomes in the diabetes study and nondiabetes control groups.

Overall, the IRs among the FDS2 participants with T2D dropped by more than 50% for all-cause mortality, myocardial infarction (MI; heart attack), stroke, hospitalization for/with heart failure, hospitalization for lower extremity amputation, and cardiovascular disease (CVD) death. Among the matched participants without diabetes, however, the stroke IR was the only measure not lower.

Broken down, for FDS2 versus FDS1, respectively, this is what the numbers (medians) show for the IRs among the T2D groups in the 2 study phases:

• MI: 1.96 (range, 1.55-2.48) versus 2.59 (range, 2.09-3.19; P = .09)
• Stroke: 1.13 (range, 0.76-1.64) versus 2.26 (range, 1.60-3.17; P = .007)
• Heart failure: 2.36 (range, 1.92-2.90) versus 2.66 (range, 2.21-3.18; P = .43)
• Lower extremity amputation: 10.3 (range, 4.11-29.2) versus 8.57 (range, 4.15-18.7; P = .72)
• CVD death: 1.66 (range, 1.15-2.36) versus 2.21 (range, 1.73-2.82; P = .17)
• All-cause mortality: 1.49 (range, 1.25-1.78) versus 1.33 (range, 1.13-1.58; P = .29)

The study authors attribute these results to improvements in the following recognized T2D risk factors from FDS1 to FDS2: hemoglobin A1C, being a smoker, Charlson Comorbidity Index score, urinary albumin:creatinine ratio, renal impairment, and atrial fibrillation. Having an Aboriginal racial background was also a positive predictor.

There were also other significant predictors of improvement, and these included lower body mass index (for the MI, CVD death, and all-cause mortality measures), being on antihypertensive therapy (for CVD death), reduced serum triglycerides (for all-cause mortality), and lower diastolic blood pressure (for HF).

"Our study found that the rate of cardiovascular complications among individuals with diabetes has declined over the past 2 decades," stated senior author Timothy M.E. Davis, FRACP, of the University of Western Australia and Fremantle Hospital in Fremantle, Australia. "While we've seen improvements in cardiovascular disease outcomes in the general population during the same time period, the gains in individuals with diabetes outpaced the general population during that timeframe."

Possible study limitations that could preclude generalizing these results to a wider population include selection bias, incomplete follow-up, misclassification of key endpoints, change in diagnostic criteria between FDS1 and FDS2, and misclassification of CVD deaths.

Reference

Davis WA, Gregg EW, Davis TME. Temporal trends in cardiovascular complications in people with or without type 2 diabetes: the Fremantle Diabetes Study [published online April 30, 2020]. J Clin Endocrinol. doi: 10.1210/clinem/dgaa215.