STOCKHOLM – Suboptimal glycemic control is an independent risk factor for a linear increase in the rate of new-onset heart failure in patients with type 2 diabetes, a large Scottish prospective case-control study indicates.
Moreover, in type 2 diabetes patients who already have established heart failure, poor glycemic control is independently associated with increased mortality, Dr. Chim Choy Lang reported at the congress.
These were the key findings in a new analysis from the Tayside Study, which Dr. Lang directs. The ongoing project provides an unusual opportunity to prospectively follow a Scottish community, population 400,000.
“We can track patients with diabetes mellitus, looking at mean [hemoglobin A1c] over time, and see who develops heart failure,” he eaid in an interview.
The analysis was performed because controversy has arisen surrounding the relationship between glycemic control in type 2 diabetes and heart failure. Some recent evidence suggests tight metabolic control is actually associated with worse survival in the setting of heart failure.
“It should be noted that most of these studies were based on a single measure of HbA1c. I think there's always cause for concern about that kind of analysis,” observed Dr. Lang, a cardiologist at the University of Dundee.
He reported on more than 9,000 Tayside residents with type 2 diabetes, 841 of whom developed heart failure during 1991-2008. Each diabetic heart failure patient was matched by age, gender, and date of diagnosis of diabetes to five controls.
Analysis, revealed that mean HbA1c during the study period was associated in linear fashion with the risk of later developing heart failure. Each 1% increase in HbA1c was independently linked to a 19% increase in incident heart failure after the researchers controlled for patients' mean arterial pressure and use of thiazolidinediones.
Further, in type 2 diabetic patients with diagnosed heart failure, each 1% increase in mean HbA1c was independently associated with an adjusted 16% increase in all-cause mortality.
“I think our findings are an argument for tight glycemic control in diabetic patients with heart failure. The question is how to achieve that. I'm a big believer in metformin for that purpose,” the cardiologist said.
Asked whether the increased risk of mortality documented in diabetic patients with poor glycemic control and heart failure is a marker for poor adherence to standard heart failure medications or is due to the adverse effects of high blood glucose, Dr. Lang said that's a key unsettled question.
“We have the ability to look at treatment adherence in this cohort and are doing so at the moment,” he added.
He declared having no financial conflicts in connection with the study, which was conducted free of industry involvement.
Each 1% increase in HbA1c was independently linked to a 19% increase in incident heart failure.
Source DR. LANG