Atherosclerotic Complication Trends in Type 2 Diabetes

There has been a general decrease in incidence of atherosclerotic complications among individuals with type 2 diabetes, with modifiable lifestyle factors attenuating risk, according to research published in Circulation.

Cardiovascular disease (CVD) continues to be one of the most common complications of type 2 diabetes mellitus (T2DM). Although recent studies have shown a decrease in risk for CVD in patients with T2DM, it remains 2 to 4 times higher in those patients compared with the general population. With limited studies of longitudinal trends of specific CVD-related event rates over time, researchers aimed to investigate the risk associations for multiple CV outcomes among individuals with T2DM, compared to age- and sex-matched control patients from the general population.

A nationwide observational study was conducted using data from the Swedish National Diabetes Registry to identify individuals from 2001 to 2019 with T2DM. Every participant was age- and sex-matched to 5 control individuals from the Statistics Sweden Statistical Database. Four nonfatal CV outcomes were assessed: coronary artery disease (CAD), acute myocardial infarction (AMI), cerebrovascular disease, and heart failure (HF). Individuals with a prior history of any outcome measure were excluded from the study.

A total of 679,072 individuals with T2DM were included in the study and matched to a cohort of 2,643,800 control patients. Mean age of patients with T2DM was 64.5 years and median follow-up was 7.1 years. Baseline prevalence of CV diagnosis was found to be twice as frequent  in the T2DM group compared with the control group. The T2DM group was also treated more often with anticoagulants, antithrombotic medications, statins, and antihypertensive medications.

Incidence rates and hazard ratios for CAD and AMI were substantially reduced in both individuals with T2DM and the control patients. Incidence rates and hazard ratios were reduced over time in both individuals with T2DM and the matched control patients. Per 10,000 person-years, risk and incidence rates for CAD decreased from 205.1 to 80.2 in patients with T2DM and from 91.2 to 37.5 in the control patients. AMI rates showed similar results, with rates reduced from 73.9 to 41.0 for individuals with T2DM and from 50.2 to 19.5 in the control patients.

Cox regression models found a stepwise reduction in hazard ratios for each 2 year period, compared with the initial time period, with an overall reduction of 50% to 60% between the first and last time periods.

There was a decrease in HF rates in patients with T2DM for the first five 2-year time periods, decreasing from 98.3 to 82.4 cases per 10,000 person years; however incidence rates then plateaued to 75.9 cases per 10,000 person years. Alternately, incidence rates of HF decreased gradually for the entire time period in the control group.

Risk factors for atherosclerotic complications, such as CAD, AMI and cerebrovascular disease, were found to be higher in patients with T2DM. They also had higher levels of hemoglobin A_1c, systolic blood pressure, LDL-C, triglycerides, and estimated glomerular filtration rate.

Some modifiable risk factors were found to increase risk for CAD. These risk factors included elevated hemoglobin A_1c, blood pressure, and LDL-C, smoking, and the albuminuria. Compared with control patients, participants with T2DM with these risk factors had a hazard ratio of 1.86 (95% CI, 1.76–1.97). These risk factors were shown to have similar outcomes after modifying outcomes for AMI and cerebrovascular disease.

Limitations of the study include lack of cardiometabolic data for control patients, which limits the ability to ascertain the extent of association between the selected risk factors and CV outcomes.

 “…the incidences of CAD, AMI, and cerebrovascular disease have declined over the past 2 decades in those with and without T2D, whereas HF appears to be increasing in recent years for people with T2D, especially in younger people who tend to be much heavier,” the study authors wrote. “To what extent greater use of newer therapies (sodium-glucose cotransporter 2 inhibitors and glucagon-like peptide-1 receptor agonists) for T2D helps to lower incident AMI and HF will be of interest to future trend analyses, including therapies that help lower weight more substantially.”