Glycaemic outcomes in people with type 2 diabetes initiating continuous glucose monitoring: The 2GO-CGM study

This is a multi-site, 12-week randomized controlled trial (RCT), followed by a 12-week continuation phase where those initially randomized to routine care cross over into the continuous glucose monitoring (CGM) intervention. This study will explore the effect of initialising CGM on glycaemic outcomes in patients with type 2 diabetes. The Dexcom G6 CGM system is being used in this study, which is already commercially available in New Zealand. All participants will be involved in the RCT for 26 weeks. The main study will be followed by a 48-month extension study, where those who volunteer to participate will use the CGM system for further 48 months. Participants who decide to take part in the extension study will be involved for a total of 5.5 years. The study will enrol 80 people with type 2 diabetes aged 16 years and over, who have suboptimal glycaemic control and inject insulin daily. Following consent, baseline data will be collected from eligible subjects during the initial clinic visit (up to 4 hours). Subjects will wear a blinded Dexcom G6 CGM system for 14 days, where the glucose values will not be shown to the participants. Following this run-in period of 14 days to collect baseline glycaemic values participants will be randomized to the control arm and continue their usual finger prick glucose monitoring, or to the intervention arm and use Dexcom G6. Participants randomized to the intervention arm will be trained on CGM use during a 3-4-hour session by trained research staff (research nurses/doctors with diabetes knowledge), and this will be combined with a diabetes management/insulin titration algorithm. Each Dexcom G6 CGM sensor can be worn for up to 10 days, and a new sensor can easily be applied by the participants themselves. The Dexcom G6 CGM system consists of (1) a sensor worn on the upper arm or abdomen that measures the glucose concentration in the interstitial fluid, (2) a transmitter that send the results wirelessly and (3) a handheld receiver, that receives and displays the glucose data. Through this receiver, CGM glucose data will be uploaded by participants to the cloud-based Dexcom CLARITY software throughout the study, and research staff will use this information to assess sensor use during the study. Throughout the 12-week RCT phase, participants will be contacted by research staff at weeks 2 and 8 to review and if required adjust the insulin titration plan as indicated by the self-management algorithm. Furthermore, all participants will be asked to complete a food diary at home on four days during both the first and the last week of the RCT phase. During the same time, sleep quality will be measured using questionnaires and actigraphy. Following the primary end-point, those in the control arm will be trained on CGM in the same way the intervention arm was originally trained and use the CGM system for 12 weeks. The intervention arm will continue Dexcom G6 use for a further 12 weeks to see if any improvements are ongoing or sustained, and allow for a longer data collected for adverse events, which occur at a very low rate. After completion of the main study, all participants will be invited into the 48-month extension study to collect longitudinal data in this population group. During the 48-month extension phase, the participants may be upgraded to the new Dexcom G7, as soon as this system is available. The Dexcom G7 is significantly smaller, has a simplified insertion process and a shorter sensor warm-up time compared to the G6 model. Any use of the Dexcom G7 would only be in the extension phase and will not induce any bias into the results given there are no differences in the glucose monitoring between the models. Those who consent to take part in the 48-month extension will visit the clinic every 6 months for a follow-up check and data collection (up to 2 hours per visit). The insulin titration algorithm is depended on the participant's diabetes treatment (basal insulin only; basal plus regimen; basal bolus regimen; once daily premixed insulin; twice daily premixed insulin). Participants will be provided with individualised plans for self-titration of their insulin regimen. Adherence and safety of self-titration will be checked at each study visit and remote review by diabetes research nurses. Prandial insulin (either rapid-acting or premixed insulin as appropriate) will be encouraged at all meals where there is a consistent > 3 mmol/L increase in glucose levels for 2 – 4 hours post meals. Non-insulin glucose lowering therapies will be continued throughout the study except for sulfonylureas, which will be stopped if prandial insulin is started at that meal. The initial insulins used in this study will be those prescribed by their normal health care providers and include: - Basal insulins – glargine (Lantus) and isophane (NPH; Protaphane; Humulin NPH) - Rapid acting insulins – aspart (NovoRapid), lispro (Humalog) and glulisine (Apidra) - Premixed insulins – 30% aspart/70% isophane (NovoMix 30), 25% lispro/75% isophane (Humalog Mix 25) and 50% lispro/50% isophane (Humalog Mix 50)