Victor W Zhong, Juhaeri Juhaeri, Stephen R Cole, Christian M Shay, Carolyn A Chew-Graham, Penny Gordon-Larsen, Evangelos Kontopantelis, Elizabeth J Mayer-Davis

PH725 / 1450 Clinical-Coded Phenotype

  1. Overview

    Phenotype Type
    Disease or syndrome
    Phenotype UUID
    Valid Event Date Range
    01/04/1997 - 31/03/2014
    Coding System
    Read codes v2
    Data Sources
    ClinicalCodes RepositoryPhenotype Library
    No data
  2. Definition


    To determine association between HbA1C variability and hypoglycemia requiring hospitalization (HH) in adults with type 1 diabetes (T1D) and type 2 diabetes (T2D).


    Using nested case-control design in electronic health record data in England, one case with first or recurrent HH was matched to one control who had not experienced HH in incident T1D and T2D adults. HbA1C variability was determined by standard deviation of ≥3 HbA1C results. Conditional logistic models were applied to determine association of HbA1C variability with first and recurrent HH.


    In T1D, every 1.0% increase in HbA1C variability was associated with 90% higher first HH risk (95% CI, 1.25–2.89) and 392% higher recurrent HH risk (95% CI, 1.17–20.61). In T2D, a 1.0% increase in HbA1C variability was associated with 556% higher first HH risk (95% CI, 3.88–11.08) and 573% higher recurrent HH risk (95% CI,1.59–28.51). In T2D for first HH, the association was the strongest in non-insulin non-sulfonylurea users (P b 0.0001); for recurrent HH, the association was stronger in insulin users than sulfonylurea users (P = 0.07). The HbA1C variability-HH association was stronger in more recent years in T2D (P ≤ 0.004).


    HbA1C variability is a strong predictor for HH in T1D and T2D.

  3. Implementation


    No data
  4. Clinical Code List