What are appropriate HbA1c targets for insulin-treated older adults?

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Takeaway

  • Among patients aged ≥65 years with insulin-treated type 2 diabetes (T2D), the relationship between HbA1c and mortality is U-shaped.

Why this matters

  • Recent guidelines call for individualized HbA1c targets for patients with T2D.

Study design

  • Data analyzed for 4589 insulin-treated adults aged ≥65 years from 532 UK General Practices via the Health Improvement Network database.
  • Funding: None disclosed.

Key results

  • Over median follow-up of 3.6 years: 
    • 1445 deaths from all causes (56/1000 person-years), and
    • 982 composite events of nonfatal myocardial infarction and stroke.
  • In adjusted model, all-cause mortality was highest in (HRs):
    • Lowest HbA1c category (
    • Highest HbA1c category (≥11.5%): 1.40 (P=.039).
  • The U-shaped relationship was not seen for the 2-point composite cardiovascular endpoint, with increased risk vs 6.5%-7.4% group seen only in the
  • Compared with the 6.5%-7.4% HbA1c group, risk for composite cardiovascular events was higher by:
    • 4% with HbA1c 7.5%-8.4%;
    • 2% with 9.5%-10.4%;
    • 12% with 10.5%-11.4%; and
    • 13% with ≥11.5%.

Limitations

  • Observational study, missing data.
  • Data from prescriptions, not adherence.
  • Factors other than HbA1c may influence insulin intensification decisions.
  • Potential unmeasured confounding, e.g., relationship of risk factors and outcomes.