Feasibility and acceptability of a novel home-based oral glucose tolerance test using continuous glucose monitoring for the diagnosis of gestational diabetes

Aim: Gestational diabetes diagnosis has been challenging during the covid-19 pandemic. We assessed the feasibility of a novel home-based OGTT using continuous glucose monitoring (CGM) to identify hyperglycaemia in pregnancy. Methods: Women with a singleton pregnancy at 28 weeks' gestation with ≥1 risk factor for gestational diabetes attending antenatal glucose testing were recruited to a pilot single-centre prospective observational study. A Dexcom G6 continuous glucose monitoring sensor was sited (receiver masked) and women were asked to take a 75g OGTT solution (Rapilose) on day four after a 10 hour overnight fast. Qualitative interviews were performed with 20 participants using telephone or video conferencing using a pre-determined interview schedule and thematically analysed using NVIVO software. Results: Forty-six women completed a home OGTT with 7.4 days of CGM. 40/46 (87.0%) took the glucose solution as instructed, and 16 (34.8%) had CGM glucose readings at 0, 60 and 120 minutes which met WHO criteria for gestational diabetes diagnosis. These women had evidence of hyperglycaemia on other CGM metrics: increased mean CGM glucose (106 vs. 92 mg/dl (5.9 vs. 5.1 mmol);p < 0.001) and time-above- range (≥140 mg/dl;≥7.8 mmol/l;6.8 vs. 2.0%;p = 0.006). Time-in- range was not significantly different. Women found the CGM painless, convenient and reassuring to use. All 20 women interviewed would recommend CGM with a home OGTT for diagnosis of gestational diabetes. Conclusions: A home-based antenatal OGTT using CGM is feasible, acceptable to pregnant women and identifies women with hyperglycaemia in pregnancy. Remote OGTTs using CGM may improve testing capacity during the covid- 19 pandemic.