VIENNA – Increasing hemoglobin A1c was directly tied to a significant increase in the risk of cardiovascular death and stroke in patients with type 2 diabetes.
For every 1% increase in HbA1c, the 4-year risk of a major cardiovascular event increased by 25%, a large prospective study has determined. The 1% increase also conferred significant increases in the risk of cardiovascular death and stroke, Dr. Nicholas Freemantle said at the annual meeting of the European Association for the Study of Diabetes.
Dr. Nicholas Freemantle
The 4-year study, however, found no increase in the risk of fatal myocardial infarction – a surprise, said Dr. Freemantle, chair of clinical epidemiology and biostatistics at University College London. It was probably a chance finding, he added.
He reported results of the Cardiovascular Risk Evaluation in People With Type 2 Diabetes (CREDIT) study. CREDIT was noninterventional, designed to evaluate real-world clinical results in patients who are newly treated with insulin. There was no fixed visit schedule, although clinicians were required to record some data every 6 months.
The cohort comprised 2,999 patients with a mean age of 61 years and a mean baseline HbA1c of 9.3%. The mean diabetes duration was about 9 years. Most of the cohort (69%) had hypertension. About half engaged in regular physical activity; 19% were smokers. Roughly one-third had at least one macrovascular disease, and 70% at least one microvascular disease.
The insulin dose increased from a median of 0.2 units/kg at baseline to 0.4 units/kg at 1 year, and to 0.5 units/kg by the end of year 4. HbA1c decreased to around 7.4% by the end of year 1 and remained stable after that.
By the end of the study, 147 major cardiovascular events had occurred. These included 60 cardiovascular deaths, 44 nonfatal MIs, and 57 nonfatal strokes. There were 148 deaths from any cause.
A multivariate model adjusted for age when starting insulin, and for baseline macrovascular disease and hypertension. It found that, for every 1% increase in HbA1c, the risk of a major cardiovascular event increased by 25%. The same HbA1c increase boosted the risk of cardiovascular death by 31% and the risk of stroke by 36%. There was no increased risk of heart attack.
Severe or symptomatic hypoglycemic events had no significant impact on the risk of cardiovascular death, Dr. Freemantle said.
CREDIT was sponsored by Sanofi. Dr. Freemantle said that he has received financial support from the company, as well as from Pfizer, Novo Nordisk, Eli Lilly, and Medtronic.
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