Managing Prediabetes: Another Way to Stave Off Heart Disease?

Prediabetes is a risk factor for all-cause death and heart-related events, a meta-analysis found.

Among the general population — those without a history of atherosclerotic cardiovascular disease — prediabetes was tied to a 13% (RR 1.13, 95% CI 1.10-1.17) higher relative risk for all-cause mortality during a median follow-up of 9.8 years, reported Xiaoyan Cai, MD, of Southern Medical University in Foshan, China, and colleagues.

The analysis of 129 studies, published online in The BMJ, also found that prediabetes in the general population was tied to a higher relative risk of experiencing several heart events:

• Composite of cardiovascular events: RR 1.15 (95% CI 1.11-1.18)

• Coronary heart disease: RR 1.16 (95% CI 1.11-1.21)

• Stroke: RR1.14 (95% CI 1.08-1.20)

Not surprisingly, these risks were magnified only in people with pre-existing atherosclerotic cardiovascular disease. The presence of prediabetes in these individuals was tied to an even higher risk for all-cause mortality (RR 1.36, 95% CI 1.21-1.54), composite cardiovascular events (RR 1.37, 95% CI 1.23-1.53), and coronary heart disease (RR 1.15, 95% CI 1.02-1.29) in a shorter follow-up period of about 3 years.

However, the risk of stroke was not associated with prediabetes status in people with pre-existing atherosclerotic cardiovascular disease (RR 1.05, 95% CI 0.81- 1.36).

The study’s senior author, Yuli Huang, MD, PhD, also of Southern Medical University, noted that the prevalence of prediabetes is increasing worldwide. “Reports estimate that more than 470 million people will have prediabetes by 2030. As [cardiologists], we know that diabetes is an important risk factor for cardiovascular disease,” he told MedPage Today, noting, though, that there are still many unknown associated risks tied to prediabetes.

However, if prediabetes is indeed associated with the risk of cardiovascular disease, it is of clinical importance to initiate prevention strategies sooner rather than later, he emphasized.

For the meta-analysis, the researchers drew on prospective cohort studies or post-hoc analyses of clinical trials, totaling over 10 million individuals. Prediabetes was defined as high fasting blood glucose according to American Diabetes Association (ADA) guidelines (100-125 mg/dL) or World Health Organization criteria (110-125 mg/dL), an impaired 2-hour glucose tolerance (140-199 mg/dL), or an elevated HbA1c level according to ADA (5.7%-6.4%) or International Expert Committee guidelines (6.0%-6.4%).

Prediabetes status was also tied to a significantly increased absolute risk for all-cause mortality compared with those with normoglycemia (7.36 per 10,000 person years, 95% CI 9.59-12.51).

Compared with normoglycemia individuals in the general population, the absolute risk of composite cardiovascular events (8.75 per 10,000 person years), coronary heart disease (6.59 per 10,000 person years), and stroke (3.68 per 10,000 person years) were also all heightened in those with prediabetes.

However, compared with normoglycemia individuals, those with prediabetes and pre-existing atherosclerotic cardiovascular disease saw the highest absolute risk differences for all outcomes:

• All-cause mortality: 66.19 per 10,000 person years

• Composite cardiovascular events: 189.77 per 10,000 person years

• Coronary heart disease: 40.62 per 10,000 person years

• Stroke: 8.54 per 10,000 person years

Prediabetes defined by impaired glucose tolerance yielded a slightly higher associated risk for all-cause mortality coronary heart disease, as well as stroke than prediabetes defined according to impaired fasting glucose. However, Huang pointed out that no matter which definition of prediabetes was used, all showed a similar prognosis in patients with a history of cardiovascular disease.

Huang said that although the findings didn’t come as much of a surprise to the researchers, they did find it interesting that in patients with atherosclerotic cardiovascular disease, the risk for all-cause mortality associated with prediabetes was higher in Asian than non-Asian patients. Although a chance finding can’t be excluded, he said, there is some previous research suggesting that this is a plausible outcome.

He added, however, that even in the general population, screening and proper management of prediabetes might be able to contribute to both primary and secondary prevention of cardiovascular disease.