For type 1 diabetics who have good glycemic control, renal function may predict their risk of developing heart disease, researchers said here.Among patients who had a lower mean glycated hemoglobin (HbA1c), those who had a lower estimated glomerular filtration rate (eGFR) were significantly more likely to develop coronary artery disease than those with a higher eGFR (P=0.006), Trevor Orchard, MD, of the University of Pittsburgh, and colleagues reported at the European Association for the Study of Diabetes meeting here.
They explained that glycemia hasn't been a consistent predictor of coronary artery disease (CAD) in type 1 diabetes, as some patients with good glycemic control still have a higher risk of heart disease.So they looked for further risk factors for CAD among 311 patients in the Epidemiology of Diabetes Complications study stratified by glycemic control. All had childhood onset type 1 diabetes without baseline heart disease.
Over the study, 82 patients developed CAD, and the overall group was divided into tertiles based on mean HbA1c (low group mean HbA1c 7.7%, high group mean HbA1c 10%).
Orchard and colleagues found that patients in the group with the highest mean HbA1c did indeed have a significantly higher incidence of CAD than those with the lowest mean HbA1c (31.9% versus 20.8%, P=0.03).In univariate analyses, both lipids and blood pressure, as well as eGFR, predicted CAD in both the high and low HbA1c groups.
But hemoglobin, hematocrit, and red and white blood cell count also predicted incident CAD in the low HbA1c group (P<0.05 for all).In adjusted analyses, only hypertension remained a significant predictor of CAD in the high HbA1c group (HR 3.6, P=0.001).In the low HbA1c group, however, both hypertension and lower eGFR were significant predictors of CAD (HR 2.4, P=0.04 and HR 1.6, P=0.02).
The researchers also found a significant interaction between HbA1c and eGFR in the low HbA1c group (P=0.006). Those who had an eGFR below 60 mL/min/1.73m2 developed CAD more frequently than did those who had a higher eGFR (53% versus 17%, P=0.003).In the high HbA1c group, that difference wasn't significant, they reported.
David Leslie, MD, of the University of London, who was not involved in the trial, said it was "intriguing" that excess mortality among those with good glycemic control seems to be related to hypertension and kidney function.
"It appears that poor glucose control is one factor in cardiovascular disease, but when control is not the factor, then other factors such as hypertension are relevant, and, notably, kidney disease, which in itself is a combination of glucose and hypertension problems," he said.