The Trend of High-Dose Insulin Usage Among Patients with Diabetes in the UK: A Retrospective Study

INTRODUCTION: Many patients with diabetes may require high-dose insulin treatment to achieve target HbA1c level, but the prevalence, disease burden, and patient characteristics of the population remain unclear. We therefore investigated people with insulin-treated diabetes in the UK from 2009 to 2013, who were prescribed high daily doses (> 200 units/day). METHODS: A retrospective analysis was conducted using the UK primary care electronic dataset from the Clinical Practice Research Datalink (CPRD). Trends of demographics, insulin dose, clinical characteristics, and annualized incidence rate of the insulin initiators were analyzed. Patients with type 1 (T1D) or type 2 diabetes (T2D) and who were prescribed insulin between 2009 and 2013 were categorized into either a low- or high-dose insulin user group. Two-sample t test and chi-square test were used for comparison of continuous variables and categorical variables, respectively. A multivariable negative binomial regression analysis with (log) person time as an offset was used to assess the impact of different covariates on incidence of high-dose insulin initiation. RESULTS: Between 2009 and 2013, 19,631 patients with diabetes were treated with insulin (T1DM, 7620; T2DM, 12,011). In 2013, 415 high-dose insulin initiators were identified (T1DM, N = 170; T2DM, N = 245). More than half were male (T1DM/T2DM, 62.4%/56.3%) and 94.1%/83.7% of T1DM/T2DM patients were prescribed an insulin analogue at high-dose insulin initiation. At 6 months, 43.6% of T1DM and 42.6% of T2DM remained to have suboptimal HbA1c level of ≥ 8% (64 mmol/mol). Overall, 15.9%/63.3% of high-dose insulin initiators (HDII) with T1DM/T2DM took oral antidiabetics. From 2009 to 2013, the estimated glomerular filtration rate worsened in both T1DM and T2DM HDII. CONCLUSION: Despite a number of patients requiring high doses of insulin in the UK, achievement of optimal HbA1c levels remains poor. Early identification of HDII is important in order to plan for alternative/adjuvant antidiabetic and lifestyle strategies to achieve optimal glycemic targets in this patient group. FUNDING: Eli Lilly and Company.