What HbA1c for the Very Elderly?

Abstract & Commentary

By Joseph E. Scherger, MD, MPH, Vice President, Primary Care, Eisenhower Medical Center, Clinical Professor, Keck School of Medicine, University of Southern California. Dr. Scherger reports no financial relationships relevant to this field of study.

This article originally appeared in the October 15, 2012, issue of Internal Medicine Alert. It was edited by Stephen Brunton, MD, and peer reviewed by Gerald Roberts, MD. Dr. Brunton is Adjunct Clinical Professor, University of North Carolina, Chapel Hill, and Dr. Roberts is Assistant Clinical Professor of Medicine, Albert Einstein College of Medicine, New York, NY. Dr. Brunton serves on the advisory board for Lilly, Boehringer Ingelheim, Novo Nordisk, Sunovion, and Teva; he serves on the speakers bureau of Boehringer Ingelheim, Lilly, Kowa, Novo Nordisk, and Teva. Dr. Roberts reports no financial relationship to this field of study.

Synopsis: In a nursing home-eligible population with a mean age of 80, those with a HbA1c between 8% and 8.9% had less functional decline than those with a HbA1c of 7% to 7.9%.

Source: Yau CK, et al. Glycosylated hemoglobin and functional decline in community-dwelling nursing home-eligible elderly adults with diabetes mellitus. J Am Geriatr Soc 2012;60:1215-1221.

The dangers of hypoglycemia are being appreciated in this era of tight control of diabetes. Efforts to achieve near normal blood sugars have become standard therapy, but when insulin is being used, episodes of hypoglycemia are more common in tightly controlled patients. We have recently appreciated the dangers of hypoglycemia in hospitalized patients and know that blood sugars in the range of 140-180 mg/dL are better than lower levels.1

Cognitive function in the elderly is fragile and hypoglycemia is especially dangerous in this group. It is estimated that 40% of persons older than age 80 have diabetes.2 Since diabetes in younger adults would be expected to reduce life expectancy below the average, those with diabetes older than age 80 are a different group and in general should be treated differently.

This group of investigators in San Francisco studied 357 elders with diabetes living in the On Lok Lifeways community for 2 years. The average age of these seniors was 80. Fifty percent (185) were taking insulin. All participants were evaluated every 6 months for functional status and control of their diabetes. Over the 2 years, 75% experienced functional decline or death. A higher HbA1c of 8-8.9% was associated with a lower likelihood of functional decline or death than those with a HbA1c of 7-7.9% (relative risk 0.88).

Commentary

Tight control of diabetes has become the standard of care for a new generation of physicians. Being in practice for more than 30 years, I remember when an HbA1c level of 8% was considered good control. Tighter control of diabetes has certainly had its benefits in reduced cardiovascular complications and infections, but like most things in medicine and life, intervention is a double-edged sword.

There is a paradox with tight control of diabetes. When aggressive lifestyle management is used, reducing body fat and even reversing the diabetes, all the outcomes are good. However, when insulin and other agents that cause hypoglycemia are used, tight control results in an increased risk of hypoglycemic episodes, a real danger for brain function.

This study is consistent with other emerging data that tight control of the advanced elderly with diabetes, especially using insulin, may be harmful. I regard my elderly patients older than 80 years with diabetes a different group from other diabetes patients and am much more relaxed with their treatment. They should be excluded from quality metrics that look at the average control of diabetes in a practice with an expected target of 7%. The American Geriatrics Society’s current recommendation is for a HbA1c of 8% or less in patients with a limited life expectancy. This recommendation appears to be too low and is likely to be revised upward.

References

1. Schmeltz LR, Ferrise C. Glycemic management in the inpatient setting. Hosp Pract 2012;40:44-55.

2. Migdal A, et al. Update on diabetes in the elderly and in nursing home residents. J Am Med Dir Assoc 2011; 12:627-632.