The in-clinic oral glucose tolerance test (OGTT) procedure is fraught with difficulties 1,2 that can cause both poor patient compliance and inaccurate test results 3,4.  

NICE guideline NG3 recommends screening of pregnant women with risk factors for gestational diabetes (GDM), using the oral glucose tolerance test (OGTT). The OGTT requires women to fast overnight and travel to a clinic in the morning where a fasting blood sample is taken, a drink containing 75g of glucose is consumed followed by a 2-hour wait in the clinic, after which a second blood sample is taken, and the test is complete. The samples are typically sent to a laboratory for testing.  

Difficulties with access to OGTT - including travel, childcare needs and cost - lead to low compliance with testing; across the various clinical applications of OGTT, compliance can range from 20% to 80% and testing is often performed much later in the pregnancy than recommended.  

OGTT is also affected by sample instability – in a recent UK NHS study it was observed that over 50% of GDM cases were missed due to glycolysis lowering the measured glucose concentrations, leading to false negative tests. 

In 2024, UK based Digostics launched “GTT@home” - the world’s first home-use OGTT -through NHS Supply Chain. The GTT@home test kit contains Digostics’ unique electronic diagnostic test platform, simple finger prickers and a premixed glucose drink - “Glucose Pro”, supplied by Una Health. GTT@home has been in use for GDM testing in the NHS since August 2024 and within a few months has raised compliance with testing from around 70% to over 97%. The GTT@home compliance with testing is the same across all ethnic groups and all indices of multiple deprivation, demonstrating universal health equity. 

GTT@home also eliminates the risk of glycolysis that leads to false negative tests, as the added fingerpick blood samples are tested immediately. Although it uses capillary blood, GTT@home is calibrated to report venous plasma equivalent glucose values, ensuring compatibility with existing laboratory-based diagnostic cut-points.  

More than 5,000 pregnant women have now used GTT@home for their routine GDM test. Of these, more than 700 returned satisfaction surveys; 92% rated GTT@home 4 or 5 out of 5; 6% were neutral. Only 2% of respondents were dissatisfied with their experience, mostly for reasons other than the home test kit. 13 survey respondents (1.8%) referred to the drink in a negative way; describing a bad taste, asking for a better taste or feeling nauseous. Many women add comments in feedback liking and even praising their home test experience and some have commented that the drink tasted nice. This feedback contrasts with the universal dislike of the in-clinic OGTT procedure. The degree of tolerance of Glucose Pro by people using GTT@home is exceptional. Digostics believes this is due to the relaxed home testing environment - replacing the stress of travel and the clinical environment with a safe and convenient home test experience - and also the palatability of the drink itself. 

The inclusion of the premixed Glucose Pro drink in the GTT@home test kit also eliminates the risk of administering an incorrect amount of glucose, which can cause inaccurate results. Standard OGTT requires 75g of glucose. There have been reports of incorrect amounts of glucose being used; 115g grammes in a recent occurrance. 

With 50% of women affected by GDM developing type 2 diabetes within 5 years, improving uptake and accuracy of OGTT should be a major NHS priority