Mixed results for insulin/dextrose infusion therapy

In patients who had an acute myocardial infarction, treatment with insulin/dextrose infusion therapy did not significantly lower mortality risk.

Issue: June 2006

Insulin/dextrose infusion therapy does not appear to offer a reduction in mortality risk in patients who recently had an acute myocardial infarction, according to a study by Australian researchers.

The study, published in Diabetes Care, was designed to examine whether improved glycemic control achieved through insulin/dextrose infusion therapy with a variable rate of insulin would help to reduce mortality in patients with hyperglycemia following an acute myocardial infarction. Previous studies have shown conflicting results regarding the benefits of various intravenous insulin therapies on this patient population.

N. Wah Cheung, PhD, from the center for diabetes and endocrinology research at Westmead Hospital in Westmead, Australia, one of the study’s researchers, told Endocrine Today that the reduction in mortality among patients who were treated with insulin/dextrose infusion therapy was not as significant as the researchers were hoping.

“The major problem we had in our study was that the patients who were randomized to insulin infusion did not have their blood glucose levels driven down low enough,” Cheung said. “This was possibly because of undue concern regarding the possibility of hypoglycemia amongst the nursing staff, and therefore aggressive titration of insulin was not maintained.”

Randomized trial

The researchers examined 240 patients who had had an acute myocardial infarction for this study. Patients eligible for the study had either diagnosed diabetes or did not have diabetes but had blood glucose levels >140.4 mg/dL.

Patients were randomly divided into two groups. The first group received insulin/dextrose infusion therapy for at least 24 hours to maintain a blood glucose level <180 mg/dL. The second group received conventional therapy.

The mean 24-hour capillary blood glucose level was 149.4 mg/dL in the patients who received insulin/dextrose infusion therapy. For patients who received conventional therapy, it was 162 mg/dL.

Insulin/dextrose infusion did not reduce mortality at the inpatient stage or at various follow-up stages. At the inpatient stage, mortality was 4.8% for the insulin/dextrose infusion group and 3.5% for patients treated with conventional therapy.

At three months, mortality levels were 7.1% for the insulin/dextrose infusion group and 4.4% for the conventional group. At six months, mortality levels were 7.9% for the insulin/dextrose infusion group and 6.1% for the conventional group.

There did appear to be benefits to insulin/dextrose infusion therapy. During the first three months, cardiac failure was 12.7% among patients in the insulin/dextrose infusion therapy group and 22.8% among patients in the conventional therapy group. Reinfarction rates during the first three months were 2.4% for the insulin/dextrose infusion therapy group and 6.1% for the conventional therapy group.

When analyzed by mean blood glucose levels achieved during the first 24 hours, mortality was reduced among subjects who achieved blood glucose levels <144 mg/dL. After six months, the mortality rate was 2% for patients who achieved this level and 11% for those who did not.

The researchers said that despite these mixed results, they still consider that tight glycemic control with insulin therapy following acute myocardial infarction may improve outcomes.

“We believe that there is sufficient evidence to support further studies into glucose lowering therapy in myocardial infarction,” Cheung said. “However, great care needs to be taken to address protocol issues and education of nursing staff to ensure that subjects assigned to tight glycemic control actually achieve glucose targets.” – by Jay Lewis

For more information:

Cheung NW, Wong VW, McLean M. The hyperglycemia: Intensive insulin infusion in infarction (HI-5) Study: A randomized controlled trial of insulin infusion therapy for myocardial infarction. Diabetes Care. 2006;29:765-770.