A pregnant pause in diabetes treatment...

Diagnosing gestational diabetes is easy, isn't it? - any degree of impaired glucose intolerance in diabetes. Well maybe, but how to define any degree of glucose intolerance in pregnancy seems to be a lot more difficult than you'd have thought.

For the clinician at the coal face in hospitals around the UK (and indeed around the world) a major factor underlying this difficulty is the vast range of discordant recommendations. In the UK, we have NICE advising us to diagnose GDM on WHO criteria, i.e. a fasting blood glucose of 7.0 and a 2 hr 75g OGTT value of 7.8. Until recently the ADA was recommending a 75 g OGTT with fasting, 1 hour and 2 hour cut offs of 5.3, 10.0 and 8.6, with 2 or more readings elevated for a diagnosis. More recently, following the publication of the HAPO study, the IADPSG have recommended cut offs of 5.1, 10.0 and 8.5 (fasting, 1hour and 2 hour respectively) on a 75 g OGTT, with only 1 level needing to be elevated for a diagnosis.

Not only is there therefore a wide range of different diagnostic criteria available, but there is an elephant in the room: adopting the IADPSG criteria will more than double the prevalence of GDM in most ante natal clinics at a stroke. When many antenatal services are already struggling to meet demand, this situation will be untenable in the short to medium term until further resources are made available.

It is therefore not surprising that some centres are sticking to old sets of diagnostic criteria and others are modifying the newer diagnostic criteria in an attempt to compromise by simultaneously adopting new criteria and managing the numbers at the same time. Anecdotally, some centres, for example are considering adopting IADPSG but stratifying cases so that 2 elevated readings would trigger entry to the antenatal diabetes clinic, 1 elevated reading would trigger mid-wife or standard antenatal clinic-led, diet-based management with potential later transfer to the antenatal diabetes clinic if acceptable glycaemic control was not being achieve.

In summary, the field is wide open and practice at present is highly variable, we desperately need authoritative practical guidance, in the meantime, the pregnant pause continues...

Dr Jeremy Turner has updated the GDM guidance on Diabetesbible. Click here to read.