Ethnic, social and multimorbidity disparities in therapeutic inertia: A UK primary care observational study in patients newly diagnosed with type 2 diabetes

Aim: To investigate factors associated with delays in receiving glucose-lowering therapy in patients newly diagnosed with type 2 diabetes mellitus (T2DM), and explore the preferential order and time of intensifications.

Materials and methods: Retrospective cohort study including 120 409 adults with T2DM initiating first- to fourth-line glucose-lowering therapy in primary care between 2000 and 2018, using the UK Clinical Practice Research Datalink linked to Hospital Episode Statistics, Office of National Statistics death registration, and 2007 Index of Multiple Deprivation data. Associations were investigated using time-to-event analysis.

Results: The longest delays to prescription of first-line therapy were observed in older patients, of black or other ethnicities, and with multimorbidity. People from the most deprived areas received earlier first-line treatment than those from the least deprived areas. The majority were treated with metformin (82.4%) as the first-line prescription, sulphonylurea (50.4%) as second-line, dipeptidyl peptidase-4 inhibitor (27.7%) as third-line, and insulin (28.0%) as fourth-line. In the past 5 years, there was an increase in prescriptions of dipeptidyl peptidase-4-inhibitor and sodium-glucose transport protein-2 inhibitor. The median time was 0.5 years for first-line prescription, 4.1 for second-line, 4.6 for third-line and 4.7 for fourth-line. After T2DM diagnosis, 25% of patients developed cardiovascular disease and non-cardiovascular disease complications within a median time of 12-14 years, and received intensification 5-6 years later.

Conclusions: Within the complex challenges of managing blood glucose levels and risk of additional comorbidities, future health care research and guidelines should focus on overcoming therapeutic inertia particularly at an earlier stage for older patients, from ethnic minorities and with multimorbidities.