This retrospective cohort study, using data from the RCGP Research and Surveillance Centre database, sought to elucidate the effects of glycaemic control within the first year of type 2 diabetes diagnosis, and subsequent trends in HbA1c variability, on cardiovascular outcomes.
A total of 26,180 adults with type 2 diabetes diagnosed between January 2005 and December 2016 were followed for a median of 4 years. Glycaemic control within the first year was categorised as good (<7.5%), moderate (7.5–9.0%) or poor (≥9.0%). Thereafter, HbA1c variability was defined by the number of times HbA1c differed between consecutive measurements by ≥5.5 mmol/mol (0.5%), adjusted for the number of measurements taken. The primary outcome was the first occurrence of major adverse cardiovascular events (MACE; myocardial infarction, coronary intervention, stroke or amputation/limb revascularisation).
The results showed that people whose HbA1c remained level or deteriorated in the first year were more likely to have a MACE event, while those whose HbA1c improved had fewer events. Subsequently, those with the greatest glycaemic variability had the greatest risk of MACE (a 51% increase compared with the lowest variability).
These findings reinforce the benefits of achieving good glycaemic control as soon as possible following diagnosis of type 2 diabetes. Thereafter, they highlight the importance of maintaining good glycaemic control over the longer term to mitigate future macrovascular risk.
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