medwireNews: Frequent fluctuations in glycated hemoglobin (HbA1c) levels between clinic visits are associated with death, cardiovascular disease, and microvascular complications in patients newly diagnosed with type 2 diabetes, a Scottish study suggests.
The real-world investigation of 21,352 patients with type 2 diabetes registered on a UK electronic health record system showed that patients for whom 60% of HbA1c measurements changed by more than 0.5% (5.5 mmol/mol) between visits were at increased risk for all 10 clinically important adverse events studied, even after adjustment of time-weighted average HbA1c.
Patients were given an HbA1c variability score (HVS) based on the number of HbA1c measures where there was at least a 0.5% change, up or down, since the last measure as a percentage of the total number of measures between diabetes diagnosis and the outcome studied.
This is in line with the standard deviation and coefficient of variation of HbA1c but is more clinically translatable, say Ewan Pearson (University of Dundee, UK) and co-researchers.
Approximately one in every eight patients had an HbA1c variability score (HVS) over 60, and for the 261 with very high variability, at an HVS of 81 to 100, the adjusted likelihood of major adverse cardiovascular events over a median follow-up of 6.8 years was increased 2.38-fold, compared with the 7084 patients in the lowest quintile, who had an HVS of 20 or less.
This increase in risk was evident across individual outcomes, at 2.40-fold for all-cause mortality, 2.40-fold for atherosclerotic cardiovascular death, 2.63-fold for coronary artery disease, 2.04-fold for ischemic stroke, 3.23-fold for heart failure, 7.40-fold for diabetic neuropathy, 3.07-fold for diabetic peripheral neuropathy, 5.24-fold for diabetic foot ulcers, and 3.49-fold for new-onset chronic kidney disease.
A sensitivity analysis including time-weighted average HbA1c from diagnosis to an adverse event confirmed the “robustness of the results,” except for the association between HVS and retinopathy, which was diminished.
Only patients with events more than 3 years after diabetes diagnosis were included in the study to rule out the potential confounding of differences in baseline characteristics.
Reporting in Diabetes Care, the researchers acknowledge the observational nature of their study but nonetheless conclude: “Our results indicate that frequent fluctuations of HbA1c of patients with diabetes may be an independent risk factor for poor prognosis, and more stable HbA1c control may benefit the patients in clinical practice.”
By Anita Chakraverty
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