Type 2 diabetes occurs when the body’s normal ways of controlling levels of sugar in the blood are not working properly. UK South Asian or African/African Caribbean groups are more likely to develop diabetes complications e.g. strokes, than European groups. Maintaining near-normal blood sugar levels is important to reduce complications in type 2 diabetes, but few studies compare long-term blood sugar levels by ethnicity. Many people with type 2 diabetes struggle to take their medication regularly, but how this impacts the way their diabetes treatment progresses has not been studied, and ethnic differences in how consistently people take their treatments are unclear.
Using electronic health records, we will compare how average blood sugar levels rise and fall over time for people of European, South Asian and African/African Caribbean ethnicity in the first five years after starting medication for type 2 diabetes. The study will also examine how any ethnic differences we find may vary by blood sugar levels at treatment commencement, age, gender, socioeconomic factors, co-existing medical conditions and medication, healthcare usage and other treatments. We will also study whether diabetes treatments are more likely to be changed if someone does not take their medication regularly, and how this varies by ethnicity.
By uncovering ethnic inequalities in blood sugar control for people with type 2 diabetes, their possible explanations and how medication-taking impacts treatment changes, we will better understand where improvements in diabetes care are needed to reduce excess complications experienced by UK South Asian and African/African Caribbean groups.
People with type 2 diabetes of UK South Asian and African/African Caribbean ethnicity experience more complications than those of European ethnicity. Cross-sectional studies demonstrate worse diabetic control (indicated by higher levels of HbA1c, a measure of the mean preceding 2-3 months’ blood glucose levels) for South Asian and African/African Caribbean than European groups. However, evidence is limited regarding ethnic differences in HbA1c trajectories, though trajectories of glucose over time are more strongly related to the likelihood of diabetes complications than one-off measurements. Moreover, a third of people with type 2 diabetes are non-adherent to glucose-lowering medication; resultant poor glycaemic control may result in unnecessary treatment intensification, but it is unclear to what extent poor adherence leads to treatment switches, and how this varies by ethnicity.
We will identify a cohort of individuals from primary care electronic medical records with incident type 2 diabetes commencing glucose-lowering medication. Ethnic differences in HbA1c trajectories in the five years following glucose-lowering medication initiation will be studied. Time to second-line glucose-lowering medication requirement according to UK national guidelines (i.e. when HbA1c>58 mmol/mol) will be compared by ethnicity. Sub-group analyses will examine how ethnic differences vary by: baseline HbA1c, socio-demographic factors, treatment factors including non-adherence, calendar period, BMI, comorbidity, polypharmacy and healthcare use. Proportions of non-adherent people receiving treatment intensification, and the determinants of inappropriate treatment intensification will be investigated.
Established algorithms and code lists will define ethnicity, diagnoses and medication use. Data will be analysed by ethnicity, using piecewise linear models to quantify HbA1c change during the first, second and third to fifth years of treatment and to determine mean time-points at which HbA1c reaches 58 mmol/mol. Stratified analyses will explore the role of potential drivers of ethnic differences in HbA1c trajectories. Logistic models will be used to investigate associations between adherence and treatment intensification.
HbA1c trajectories during first/ second/ third to fifth years of glucose-lowering medication use; time-points at which HbA1c reached 58 mmol/mol (second-line therapy threshold); overall HbA1c trajectory; glucose-lowering treatment intensification
Krishnan Bhaskaran - Chief Investigator - London School of Hygiene & Tropical Medicine ( LSHTM )
Krishnan Bhaskaran - Corresponding Applicant - London School of Hygiene & Tropical Medicine ( LSHTM )
Liam Smeeth - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Nishi Chaturvedi - Collaborator - University College London ( UCL )
Rohini Mathur - Collaborator - Queen Mary University of London
Sophie Eastwood - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Patient Level Index of Multiple Deprivation;Practice Level Index of Multiple Deprivation