Tuberculosis Drug Levels and Continuous Glucose Monitoring in Diabetic Patients

This study has been designed as a case control trial analysed via population pharmacokinetic modelling, with the hypothesis that overall exposure to TB medications will be lower in the diabetic than the non-diabetic group. Non-Diabetic group (controls): This group will be asked to take their TB medications as usual, and return at weeks 2 and 8 (timed to fit with routine appointments) and week 16. On these days, participants will be asked to record a video or to call the study team when taking the TB medications, so that the time can be recorded, and will then attend later in the day for routine bloods (week 2 and 8) and trial bloods taken at the same time (trial bloods only at week 16). At each visit, consent will be checked, the participant will be weighed and current medications will be checked. Venepuncture will be carried out for scheduled blood tests and for TB drug levels. With the participant's consent, a further blood sample will be taken later in the day for TB drug levels in addition. Diabetic group (cases): The diabetic group will undertake the same visits as the control group, with 2 additional features. Part of the same blood samples taken for TB drug levels will be used to measure oral diabetes drug levels in participants established on oral diabetes medication. These participants will be asked to attend an additional visit after the baseline visit but prior to starting TB treatment. Participants will be asked to record (again via video or call to the team) the time the evening diabetes medications were taken, to omit the morning dose and then to attend for a blood sample for a baseline diabetes medication level. Diabetic patient will also wear a blinded continuous glucose monitor (CGM) for 10 days at baseline and at week 16. Participants will be trained, and at weeks 0 and 16, the study co-ordinator will apply the sensor and transmitter, which will be worn for the next 10 days. The data will then be analysed to compare week 0 with week 16. Corticosteroid Subgroup: As a pilot project, any patients commencing on TB therapy who are also receiving corticosteroids as part of TB treatment, will be approached to follow the sample schedule as the control group. Blood samples will be processed within 30 minutes of venepuncture, and the serum fraction (which contains the medications) will be frozen to -20C at the on-site laboratory. Frozen samples will be transported to the testing laboratory in appropriately labelled containers. Batches of samples will be analysed using high performance liquid chromatography for TB and diabetes drug levels.