(HealthDay News) — Time-updated hemoglobin A1c (HbA1c) variables have a stronger association with myocardial infarction (MI) than baseline HbA1c, according to a study published online May 26 in Diabetes Care.

Marita Olsson, PhD, from R&D AstraZeneca in Mölndal, Sweden, and colleagues examined the risk of MI by impaired glycemic control in a cohort of patients with type 2 diabetes, diagnosed between 1995–2001, using data from the Clinical Practice Research Data (CPRD) Link in the United Kingdom (101,799 participants). Participants were divided into an early cohort (diagnosed from 1997–2004) and a recent cohort (diagnosed from 2004–2011). The correlation between three HbA1c metrics and MI was examined.

The researchers found that the risk increase for MI per 1% increase in HbA1c was higher for updated latest and updated mean HbA1c than for baseline HbA1c (1.11 and 1.15, respectively, vs. 1.05), in the overall cohort. The corresponding risk estimates were greater in the early vs. the recent cohort. In the recent, but not the early, cohort the updated latest variable showed an increased risk for HbA1c <6%, relative category 6–7% (hazard ratios, 1.23 [95% confidence interval, 1.08–1.40] and 1.01 [95% confidence interval, 0.84–1.22], respectively).

“The two time-updated HbA1c variables show stronger associations with risk of MI than baseline HbA1c, and the association between HbA1c and risk of MI has decreased over time,” the authors write.

Several authors disclosed financial ties to pharmaceutical companies, including AstraZeneca, which funded access to the CRPD database.

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