Glycosylated hemoglobin and functional decline in community-dwelling nursing home-eligible elderly adults with diabetes mellitus

Objectives: To determine whether glycosylated hemoglobin (HbA1c) levels predict functional decline in older adults.

Design: Longitudinal cohort study.

Participants: Community-dwelling, nursing home (NH)-eligible individuals with diabetes mellitus enrolled at On Lok between October 2002 and December 2008 (367 participants, 1,579 HbA1c measurements).

Setting: On Lok Lifeways, the original model for Programs of All-Inclusive Care for the Elderly.

Measurements: The outcomes were functional decline or death at 2 years. The primary predictor was HbA1c. Age, sex, race and ethnicity, baseline function, comorbid conditions, length of time enrolled at On Lok, insulin use, and clustering of HbA1c within participants were adjusted for with mixed-effects Poisson regression.

Results: Mean age was 80, and 185 participants (50%) were taking insulin. Sixty-three percent of participants experienced functional decline, and 75% experienced death or functional decline during the study period. At 2 years, higher HbA1c was associated with less functional decline or death (P for trend = .006). Accounting for clustering and confounding factors, HbA1c of 8.0% to 8.9% was associated with a lower likelihood (relative risk = 0.88, 95% confidence interval = 0.79-0.99) of functional decline or death than HbA1c of 7.0% to 7.9%.

Conclusion: In community-dwelling, NH-eligible individuals with diabetes mellitus, HbA1c of 8.0% to 8.9% is associated with better functional outcomes at 2 years than HbA1c of 7.0% to 7.9%, suggesting that the current American Geriatrics Society guideline recommending a HbA1c target of 8.0% or less for older adults with limited life expectancy may be lower than necessary to maintain function.