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Tight Blood Glucose Control and Cardiovascular Disease

How low should we go?

A new study is a 10-year follow-up to the Veterans Affairs Diabetes Trial in which 1,791 type 2 diabetics over the age of 60 were enrolled. The veterans were randomly placed in either the “standard” therapy group that had a higher HbA1c goal or the “intensive” treatment group who had a lower HbA1c goal. Throughout the 5½ year trial, the average HbA1c for the intensive treatment group was close to 6.9% while the standard treatment group had an average HbA1c of nearly 8.4%.

Most of the participants, ~1,600, were followed for an additional five years to determine how many had a cardiovascular event and researchers compared these findings between the two groups. Results showed that those in the intensive treatment group had a 17% reduction in the risk for a heart attack or stroke compared with those in the standard treatment group.

Following the 5½ year initial study, veteran participants were no longer supervised in their medical care and HbA1c levels in the intensive treatment group began to climb and still they continued to reap the benefits of early on tight control. Dr. David Nathan, Director of the General Clinical Research Center and the Diabetes Center at Massachusetts General Hospital and Professor of Medicine at Harvard Medical School, calls this response “metabolic memory.” “An early period of intervention seems to have durable effects over time,” he said.

He also warns that these positive effects on the cardiovascular system do not last forever, but the longer blood sugar is kept under tight control, the longer benefits will be seen. This tight control can also be dangerous and patients are at an increased risk for hypoglycemia.

Practice Pearls:

  • A five-year follow-up study showed that tight glucose control reduces the risk for cardiovascular complications by 17%.
  • Intensive treatment reduced cardiovascular disease in veterans with poorly controlled diabetes, however hypoglycemia becomes more of a risk.
  • “Metabolic memory” may explain why an early period of tight control can have lasting effects over time, but not indefinitely.

Rodney A. Hayward. Follow-up of Glycemic Control and Cardiovascular Outcomes in Type 2 Diabetes. N Engl J Med 2015; 372:2197-2206 June 4, 2015 DOI: 10.1056/NEJMoa1414266.