People with prediabetes, defined by having a hemoglobin A1c of 5.7%-6.4%, had a significantly increased rate of atherosclerotic cardiovascular disease events and incident chronic kidney disease in a study of nearly 337,000 people included in the UK Biobank database.
The findings suggest that people with prediabetes have “heightened risk even without progression to type 2 diabetes,” Michael C. Honigberg, MD, said at the annual scientific sessions of the American College of Cardiology.
“Hemoglobin A1c may be better considered as a continuous measure of risk rather than dichotomized” as either less than 6.5%, or 6.5% or higher, the usual threshold defining people with type 2 diabetes, said Honigberg, a cardiologist at Massachusetts General Hospital in Boston.
“Prediabetes Is Not a Benign Entity”
“Our findings reinforce the notion that A1c represents a continuum of risk, with elevated risks observed, especially for atherosclerotic cardiovascular disease [ASCVD], at levels where some clinicians wouldn’t think twice about them. Prediabetes is not a benign entity in the middle-aged population we studied,” Honigberg said in an interview. “Risks are higher in individuals with type 2 diabetes,” he stressed, “however, prediabetes is so much more common that it appears to confer similar cardio, renal, and metabolic risks at a population level.”
Results from prior observational studies also showed elevated incidence rate of cardiovascular disease events in people with prediabetes, including a 2010 report based on data from about 11,000 U.S. residents, and in a more recent meta-analysis of 129 studies involving more than 10 million people. The new report by Honigberg “is the first to comprehensively evaluate diverse cardio-renal-metabolic outcomes across a range of A1c levels using a very large, contemporary database,” he noted. In addition, most prior reports did not include chronic kidney disease as an examined outcome.
The primary endpoint examined in the new analysis was the combined incidence during a median follow-up of just over 11 years of ASCVD events (coronary artery disease, ischemic stroke, or peripheral artery disease), CKD, or heart failure among 336,709 adults in the UK Biobank who at baseline had none of these conditions nor type 1 diabetes.
The vast majority, 82%, were normoglycemic at baseline, based on having an A1c of less than 5.7%; 14% had prediabetes, with an A1c of 5.7%-6.4%; and 4% had type 2 diabetes based on an A1c of at least 6.5% or on insulin treatment. Patients averaged about 57 years of age, slightly more than half were women, and average body mass index was in the overweight category except for those with type 2 diabetes.
The primary endpoint, the combined incidence of ASCVD, CKD, and heart failure, was 24% among those with type 2 diabetes, 14% in those with prediabetes, and 8% in those who were normoglycemic at entry. Concurrently with the report, the results appeared online. Most of these events involved ASCVD, which occurred in 11% of those in the prediabetes subgroup (roughly four-fifths of the events in this subgroup), and in 17% of those with type 2 diabetes (nearly three-quarters of the events in this subgroup).
In an analysis that adjusted for more than a dozen demographic and clinical factors, the presence of prediabetes linked with significant increases in the incidence rate of all three outcomes compared with people who were normoglycemic at baseline. The analysis also identified an A1c level of 5.0% as linked with the lowest incidence of each of the three adverse outcomes. And a very granular analysis suggested that a significantly elevated risk for ASCVD first appeared when A1c levels were in the range of 5.4%-5.7%; a significantly increased incidence of CKD became apparent once A1c was in the range of 6.2%-6.5%; and a significantly increased incidence of heart failure began to manifest once A1c levels reached at least 7.0%.
Need for Comprehensive Cardiometabolic Risk Management
The findings “highlight the importance of identifying and comprehensively managing cardiometabolic risk in people with prediabetes, including dietary modification, exercise, weight loss and obesity management, smoking cessation, and attention to hypertension and hypercholesterolemia,” Honigberg said. While these data cannot address the appropriateness of using novel drug interventions in people with prediabetes, they suggest that people with prediabetes should be the focus of future prevention trials testing agents such as sodium-glucose cotransporter 2 inhibitors.
“These data help us discuss risk with patients [with prediabetes], and reemphasize the importance of guideline-directed preventive care,” said Vijay Nambi, MD, PhD, a preventive cardiologist and lipid specialist at Baylor College of Medicine and the Michael E. DeBakey VA Medical Center in Houston, who was not involved with the study.
An additional analysis reported by Honigberg examined the risk among people with prediabetes who also were current or former smokers and in the top tertile of the prediabetes study population for systolic blood pressure, high non-HDL cholesterol, and C-reactive protein (a marker of inflammation). This very high-risk subgroup of people with prediabetes had incidence rates for ASCVD events and for heart failure that tracked identically to those with type 2 diabetes. However. the incidence rate for CKD in these high-risk people with prediabetes remained below that of patients with type 2 diabetes.
Honigberg had no disclosures. Nambi has received research funding from Amgen, Merck, and Roche.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.
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