Abstract

Objective: To evaluate association of visit-to-visit HbA1c variability and absolute changes in HbA1c with poor glycemic control in patients with diabetes. Study design: A retrospective cohort study. Methods: Healthcare claims data for all diabetes patients aged 65 years or older and continuously enrolled in Medicare Advantage plans in Independence Blue Cross from 2013 to 2014 and had ≥ 3 HbA1c measurements in the 2013 measurement year (MY). We used patients' zip codes to link to US census data to get socioeconomic status information. Poor glycemic control was identified as the most recent HbA1c level > 9.0% during the MY. HbA1c variability was defined as within-subject standard deviation of HbA1c levels; absolute change in HbA1c was defined as the difference between the most recent HbA1c level and the first HbA1c level measured in MY2013. Multivariable logistic regression models were created, with poor glycemic control in MY2014 as the outcome. Results: Among the cohort composed of 4,458 patients enrolled in the plans in both 2013 and 2014, the mean age was 78.3 years, with 45.6% male. A total of 21.9% of patients had poor glycemic control in MY2014. Increasing quintiles of HbA1c variability are associated with both increased mean HbA1c and absolute change in HbA1c (both p < 0.0001). The proportion of poor glycemic control increased with increased quintile of HbA1c variability ( p < 0.0001). After adjusting by confounders, HbA1c variability was not associated with increased poor glycemic control in the subsequent year (adjusted OR = 0.98, 95% CI: 0.69-1.38 for the highest quintile), whereas mean HbA1c and absolute change in HbA1c were both associated (adjusted OR = 1.68 (95% CI: 1.51-1.88) for mean; adjusted OR = 1.14 (95% CI: 1.03-1.26) for change). Conclusion: Mean HbA1c and absolute change in HbA1c were both associated with poor glycemic control, whereas HbA1c variability was not.

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