Clinical question
What are reasonable hemoglobin A1c (HbA1c) targets for patients with type 2 diabetes mellitus?
Bottom line
While many patients safely attain HbA1c levels at or just below 7%, for older patients with long-standing diabetes, multiple comorbidities, and high risk of hypoglycemia, reasonable targets are 7% to 8% or higher.
Evidence
Intense management of blood glucose in type 2 diabetes was examined in 10 meta-analyses.1
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Patients varied by age, comorbidities, medications, etc, making evidence interpretation and application difficult. Five reasonably sized trials fall into 2 groups:
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Patients in their 50s newly diagnosed with diabetes with few comorbidities randomized to 1 glucose-lowering therapy or diet control, followed for about 17 years (outcomes reported as 10-year rates).
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Patients with established diabetes in their 60s with more comorbidities receiving multiple glucose-lowering therapies for intense versus conventional therapy.
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-ACCORD5 (N = 10 251): 3.5 years, HbA1c 6.4% versus 7.5%.
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-ADVANCE6 (N = 11 140): 5 years, HbA1c 6.5% versus 7.3%.
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-Veterans7 (N = 1791): 5.6 years, HbA1c 6.9% versus 8.4%.
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-Intense management led to prevention of visual deterioration (NNT = 60) and loss of light-touch sensation (NNT = 49)8; no benefit in CV outcomes5–7 except reduced nonfatal MI in 1 study (NNT = 100)6; worsening mortality5 (NNH = 96) and hospitalization6 (NNH = 48); and weight gain (1 in 8 gained ≥ 10 kg5) and hypoglycemia (severe5; NNH = 15).5–7
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Context
Implementation
New guidelines12,13 recommend less stringent targets (eg, 7.1% to 8.5%) in patients with shorter life expectancy, increased comorbidities, increased functional dependency, and high risk of hypoglycemia or other adverse events. In elderly patients with diabetes with HbA1c of 7.0% or lower, reduction of diabetic medications for modest HbA1c control addresses risk of hypoglycemia, polypharmacy, falls, functional decline, adverse cardiovascular outcomes, and mortality. First steps include reducing insulin or sulfonylureas to minimize hypoglycemia risk, or reducing thiazolidinediones to minimize heart failure or fracture risk. As targets and therapy are individualized, HbA1c targets of 7% or lower as quality indicators should be reconsidered.
Notes
Tools for Practice articles in Canadian Family Physician (CFP) are adapted from articles published on the Alberta College of Family Physicians (ACFP) website, summarizing medical evidence with a focus on topical issues and practice-modifying information. The ACFP summaries and the series in CFP are coordinated by Dr G. Michael Allan, and the summaries are co-authored by at least 1 practising family physician and are peer reviewed. Feedback is welcome and can be sent to toolsforpractice{at}cfpc.ca. Archived articles are available on the ACFP webte: www.acfp.ca.
Footnotes
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This article is eligible for Mainpro-M1 credits. To earn credits, go to www.cfp.ca and click on the Mainpro link. This article is eligible for Mainpro-M1 credits. To earn credits, go to www.cfp.ca and click on the Mainpro link.
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La traduction en français de cet article se trouve à www.cfp.ca dans la table des matières du numéro de novembre 2013 à la page e492.
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The opinions expressed in Tools for Practice articles are those of the authors and do not necessarily mirror the perspective and policy of the Alberta College of Family Physicians.
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