A couple of weeks ago in the clinic we had a woman, just over three months gestation, who was diagnosed with gestational diabetes (GDM). She had GDM on the last pregnancy when it was found at 28 weeks so was surprised when she got it so early this time round. What is going on?
Gestational diabetes occurs when a pancreas that is not able to make extra insulin is confronted by the normal insulin resistance of pregnancy. The hormones coming from the placenta cause the insulin resistance and these usually rise in the second three months of pregnancy and so typically GDM is diagnosed at 24 to 28 weeks of pregnancy. The major issue is how the pancreas is working. A healthy pancreas can cope with a huge amount of insulin resistance such as seen in late pregnancy especially if the mom is over weight. However if the problem resides in the pancreas then it takes only a little insulin resistance to tip the balance and end up with GDM.
A diagnosis of GDM on one pregnancy has now identified someone with a suspect pancreas. As we age our pancreas works less well so on any subsequent pregnancy the woman is older and her pancreas will not work as well. Hence we expect GDM to occur at an earlier gestational age and if the person has gained some extra weight (which causes insulin resistance) the GDM will present even earlier. However, forewarned is forearmed: if it is know that the woman has a high chance of GDM it can be checked for sooner and looked after before it does any harm. Because this person’s pancreas has now to face the insulin resistance of pregnancy getting stronger in later pregnancy most of these women need either tablets or insulin to handle their GDM.
There are two things to be careful about. Firstly, if GDM occurs at this early stage before the pregnancy is really causing much in the way of insulin resistance then the problem with the pancreas making enough insulin is quite significant and it is very important for these women with an early diagnosis of GDM to have testing postpartum to make sure there is not diabetes or glucose intolerance persisting and have it dealt with if present. Secondly, in this setting of an early diagnosis of GDM the question arises whether the woman actually had glucose intolerance or diabetes pre pregnancy and the risks associated with Type 2 diabetes and pregnancy. That is why in our clinic in this situation we measure the A1c, a blood test that tells how the blood sugar has been over the last three months. A normal A1c means all was fine.
Early GDM means longer time spent monitoring and paying attention to diet, it also gives more time to control things and get a good outcome, a healthy baby.