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Identifying the independent effect of HbA 1c variability on adverse health outcomes in patients with Type 2 diabetes
Author(s) -
Prentice J. C.,
Pizer S. D.,
Conlin P. R.
Publication year - 2016
Publication title -
diabetic medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.474
H-Index - 145
eISSN - 1464-5491
pISSN - 0742-3071
DOI - 10.1111/dme.13166
Subject(s) - medicine , quartile , hazard ratio , stroke (engine) , diabetes mellitus , type 2 diabetes , ambulatory , veterans affairs , myocardial infarction , cohort , confidence interval , endocrinology , mechanical engineering , engineering
Aims To characterize the relationship between HbA 1c variability and adverse health outcomes among US military veterans with Type 2 diabetes. Methods This retrospective cohort study used Veterans Affairs and Medicare claims for veterans with Type 2 diabetes taking metformin who initiated a second diabetes medication ( n = 50 861). The main exposure of interest was HbA 1c variability during a 3‐year baseline period. HbA 1c variability, categorized into quartiles, was defined as standard deviation, coefficient of variation and adjusted standard deviation, which accounted for the number and mean number of days between HbA 1c tests. Cox proportional hazard models predicted mortality, hospitalization for ambulatory care‐sensitive conditions, and myocardial infarction or stroke and were controlled for mean HbA 1c levels and the direction of change in HbA 1c levels during the baseline period. Results Over a mean 3.3 years of follow‐up, all HbA 1c variability measures significantly predicted each outcome. Using the adjusted standard deviation measure for HbA 1c variability, the hazard ratios for the third and fourth quartile predicting mortality were 1.14 (95% CI 1.04, 1.25) and 1.42 (95% CI 1.28, 1.58), for myocardial infarction and stroke they were 1.25 (95% CI 1.10, 1.41) and 1.23 (95% CI 1.07, 1.42) and for ambulatory‐care sensitive condition hospitalization they were 1.10 (95% CI 1.03, 1.18) and 1.11 (95% CI 1.03, 1.20). Higher baseline HbA 1c levels independently predicted the likelihood of each outcome. Conclusions In veterans with Type 2 diabetes, greater HbA 1c variability was associated with an increased risk of adverse long‐term outcomes, independently of HbA 1c levels and direction of change. Limiting HbA 1c fluctuations over time may reduce complications.