Q:  Hiya, can I ask what your views are on gestational diabetes (GD), and routine as opposed to symptom based testing of? Sorry it’s a bit random, I am just desperately trying to find different views, I have 1 team telling me it is life threatening to both baby & mum and everybody ought to have a test, and one side telling me its harmless and mostly made up and there is no improved outcome for babies or mums if interventions are offered. Please help?

–          Anonymous by Request

A:  The first thing that is very important to realize, which was brought to my attention from my own set of midwives when I was pregnant, is that people really don’t know much about what levels are harmful for pregnant women.  There has been one big study on glucose levels in pregnant women which examined over 25,000 women and found increased risk of high birth weight (> 90th percentile), c-section, and high cord-blood syrum C peptide (insulin resistance) (though they report an increased risk for neonatal hypoglycemia but looking at the data, it’s not significant) based on increasing levels of blood sugar.  What does this mean?  Well, it’s hard because certain elements here, like the c-section, may be a result of being induced because one had GD and induction is highly linked to c-section rates (though this one study did keep caregivers blind to the status provided women didn’t meet the full criteria for diabetes).  As for the infant outcomes, GD alone does not lead to later metabolic problems.  In one long-term study of GD and birth weight, it was found that the combination of high birth weight and GD (or high birth weight and maternal obesity with no GD) predicted metabolic problems in children at age 11.  Importantly, GD alone was not predictive of insulin resistance or later childhood obesity.  Based on this study, though, the American Diabetes Associated updated its levels for pregnant women—lowering them for a diagnosis—and continued their suggestion that all pregnant women be tested.  However, the idea that it is life threatening is bogus.  This study did look at mortality and found a ZERO relationship with GD.  So you need not worry about that.

The second thing to consider is that the vast majority of GD cases disappears after pregnancy with no intervention and have no symptoms.  The failure of the aforementioned study was that it did not take into account any symptoms these mothers had – it is quite likely that mothers on the upper end of the blood sugar levels did show symptoms and thus should have been tested.  But importantly, because the negative outcomes are still small and many people have no symptoms, the stress of knowing one has GD may pose more problems to mom and baby when not accompanied by symptoms.  Especially when caregivers have been known to do things like induce because of GD, despite the evidence that GD alone does not require inductions.   A further complication which may eventually explain some of these findings is that Type 2 diabetes is on the rise and the American Diabetes Association expects that many people who have it are simply not diagnosed.  Pregnancy may be the first time they are tested and because the body seems to lower its blood sugar levels in pregnancy, many of these women may not show clinical levels of glucose, but be given the GD label.  What would lead people to believe this is the case?  Primarily it has to do with the low number of women with GD who have any symptoms, the linear relationship of negative outcomes with symptoms, and the fact that the negative outcomes of GD are exactly the same as those of women who have been diagnosed with diabetes pre-pregnancy.

A third and final thing to consider is that the treatment for very mild GD (i.e., no symptoms) is diet and exercise.  Insulin is only given as needed.  So, if you plan on eating correctly and making sure you get enough exercise, you’ll be lowering the risk of any complications, though the research on whether any treatment helps is mixed.  Some have found better outcomes with treatment (dietary and insulin if needed) while others have found no differences in treatment versus control groups who continue to receive the usual prenatal care.  This is probably why the health departments in many countries, including Canada and the UK, have statements questioning the validity of routine testing.  Important to note here is that all pregnant women should be eating properly and getting enough exercise – it’s key to lowering any complications during delivery and simply ensuring the health of yourself and your baby.  You shouldn’t need a test to remind you to do that.

In sum, I see no reason for any woman to undergo routine GD testing.  If you do start to notice symptoms, however, you should be tested immediately because it’s no longer mild and there may be serious complications and insulin treatment may be necessary.  But given that the first step of treatment with no symptoms is diet and exercise, if you undertake that right from the get-go, you will be doing exactly what was recommended anyway.  Getting the test done also puts more power in the hands of your caregiver, as once you have that diagnosis, they can use that to demand inductions even with no other symptoms.  I should mention one more thing – if getting the test puts you at ease, then do it.  Rarely is that the case, but if you believe knowing will make you less stressed, you should go ahead and get it done (though I wouldn’t recommend the fasting test, most care providers seem to agree that any fasting test in pregnancy is not a good idea) because stress is definitely not what you need during your pregnancy.

Symptoms of Gestational Diabetes:

  • Increased thirst
  • Increased hunger
  • Increased urination
  • Weight loss (coupled with increased appetite)
  • Blurred vision
  • Fatigue
  • Nausea
  • Vomiting
  • Frequent bladder, vaginal, or skin infections

While many of these are common in late pregnancy, some are not and the severity to which you have them should help establish whether further testing is necessary.  Please talk to your health care provider at all stages though.

Recommended Reading After Sources



American Diabetes Association. Diagnoses and classification of Diabetes Mellitus.  Diabetes Care 2012; 35: s64-s71.

Boney CM, Verma A, Tucker R, Vohr BR.  Metabolic syndrome in childhood: Association with birth weight, maternal obesity, and gestational diabetes mellitus.  Pediatrics 2005; 115: e290-e296.

Crowther CA, et al. Effect of treatment of gestational diabetes mellitus on pregnancy outcomes.  New England Journal of Medicine 2005; 352: 2477-86.

Landon MB, et al. A multicenter, randomized trial of treatment for mild gestational diabetes.  New England Journal of Medicine 2009; 361: 1339-48.

Metzger BE, et al. International association of diabetes and pregnancy study groups recommendations on the diagnosis and classification of hyperglycemia in pregnancy.  Diabetes Care 2010; 33: 676-82.

The HAPO Study Cooperative Research Group.  Hyperglycemia and adverse pregnancy outcomes.  New England Journal of Medicine 2008; 358: 1991-2002.