Abnormal glucose levels common in ‘nondiabetic’ PCI patients, tied to worse outcomes

Roughly one-third of patients without known diabetes in a PCI trial had abnormal glucose readings and demonstrated up to a four-fold risk of adverse outcomes within one year, researchers reported in JACC: Cardiovascular Interventions.

The study raises the question of whether prediabetes or previously undetected, “silent” diabetes should be determined via routine glucose testing before PCI, wrote senior author Kenneth Tandjung, MD, PhD, and colleagues.

The trial included 988 participants who received oral glucose tolerance testing (OGTT) four to six weeks after PCI and assessment of hemoglobin A1c (HbA1c) with fasting plasma glucose. By either of these approaches, 33.4 percent of patients had abnormal glucose metabolism, 7.2 percent of which had silent diabetes.

Compared to people with normal glucose tolerance, those with previously undetected silent diabetes had an adjusted 4.2-fold risk of meeting the primary endpoint of cardiac death, target vessel-related MI or target vessel revascularization within one year. The odds of meeting that combined endpoint were 13.2 percent, 7.6 percent and 4.8 percent for diabetes, prediabetes and normal glucose levels, respectively, as assessed by OGTT. Corresponding rates for the hemoglobin and fasting plasma glucose test were similar but marginally lower in each category.

The increased odds for adverse events in the diabetes cohort were largely driven by target-vessel MIs within 48 hours of PCI. Tandjung et al. noted the one-year mortality risk was low across all three groups.

“Silent diabetic patients comprised 7 percent of the study participants and accounted for 23% of all primary endpoints,” they wrote. “The findings of the prospective BIO-RESORT Silent Diabetes study underline the importance of previously unknown (and untreated) diabetes for clinical outcome after PCI, performed with contemporary DES (drug-eluting stents) that recently demonstrated excellent safety and efficacy.”

Biodegradable polymer and durable polymer DES were used in the trial, which studied outcomes among a predominantly white population in the Netherlands. The authors said this is notable because the Netherlands boasts lower diabetes rates than the U.S. and many other European countries, and is typically good about screening for many common diseases including diabetes. For these reasons, they noted, “it is fair to assume that the proportion of silent diabetics among PCI patients may be higher than 7 percent, both in countries with a higher diabetes risk or more difficult access to primary care.”

Indeed, the authors highlighted previous PCI studies which showed a range in silent diabetes from 9.2 percent to 29 percent, with those patients commonly demonstrating a higher risk for adverse outcomes.

“Our findings suggest that screening for abnormal glucose metabolism may be advisable, as it was associated with an increased adverse event risk—in particular of periprocedural MI,” Tandjung and coauthors wrote. “The lipid-rich plaque composition and the hypercoagulable state augment the atherothrombotic risk in patients with hyperglycemia and diabetes and might have contributed to our findings. Others have also postulated that pre-diabetes poses an increased risk for cardiovascular events, justifying efforts to improve glucose metabolism and delay conversion to diabetes.”

The authors said OGTT may detect more people with diabetes than HbA1c testing, but the latter is less expensive and has shown to have a lower measurement variation. In a perfect world, they said, these tests would be complementary because they can detect different patients. However, they acknowledged OGTT is more labor intensive and “onerous on patients,” and is therefore more difficult to incorporate into everyday practice.