GESTATIONAL DIABETES

Gestational diabetes is defined as diabetes diagnosed during pregnancy.  The great majority of the time it resolves as soon as the baby is born.  The baby is NOT born with diabetes. 

Gestational diabetes ("GDM") is typically picked up during routine screening.  Most moms, at some point during their 24th-28th weeks of pregnancy will be asked to drink a sugar-rich product (containing 50 grams of sugar) and then, an hour later, will have blood taken to measure their blood glucose level.  If the blood glucose level is above 7.7 this is considered abnormal, but in and of itself does not make a diagnosis of GDM.  Rather a confirmatory test is done wherein the mom drinks an even richer drink (containing 75 gms of carbohydrate) and they have blood sugar levels taken three times over 2 hours.  If two or more of the blood glucose readings are high then a diagnosis of GDM is made.

GDM often occurs in people with some risk factor(s) for diabetes (particularly type 2 diabetes).  These risk factors include having a family history of diabetes or being overweight.  Nonetheless, it is not uncommon for women with GDM to have no risk factors for diabetes.

What is the importance of GDM?  Well, first of all, most moms with GDM have otherwise uneventful pregnancies and healthy babies.  That is, everything goes just fine.  But potentially GDM can lead to the fetus being large (if the mom's blood sugar level is high then sugar goes from the mom into the fetus-sort of like overfeeding the baby while it's still inside the uterus) which can make delivery more difficult.  There is also an increased risk of the baby being born with low blood sugar (usually easily treated by giving the baby sugar water to drink) which generally is not a problem after a day or two.  Other complications are less frequent and include the baby having jaundice or, infrequently, having a calcium imbalance. 

We treat GDM by having the mom's diet modified and teaching the mom to test her own blood sugar levels (my preference is for measurements before and two hours after breakfast, but sometimes other times are used) using a blood glucose meter.  If they are normal, no other treatment is necessary.  If they are too high then insulin therapy is typically prescribed.  It is very important to recognize that GDM is CURED by giving birth and insulin is virtually never required after delivery.  I send ALL my patients with GDM to the pregnancy program at the diabetes education centre where they are taught about the condition and its management and followed along during the pregnancy.

Post-delivery the mom can usually return to a conventional (BUT HEALTHY) diet.  I usually have the mother check her blood glucose level before breakfast for a couple of days and, if it is remaining normal, routine day-to-day monitoring is seldom necessary thereafter.  About two months after birth, I recommend the mom have a glucose tolerance test ("GTT") performed (essentially the same test that was done when the diagnosis of GDM was made during pregnancy) to be extra certain things have returned to normal.  I also recommend that an annual fasting blood glucose be done and that the mother's glucose status be assessed prior to attempting any further pregnancies.  Surprisingly, many women do not re-develop GDM with subsequent pregnancies (but they need to be monitored carefully to make sure).

A crucial thing to be aware of is that if you have gestational diabetes, that is a strong clue that you are at risk of developing Type 2 diabetes.  That risk can be as low as about thirty per cent and as high as about seventy per cent.  If, post-delivery, you follow a careful lifestyle, stay physically active (and hey, aren't most moms?), eat properly and get down to and maintain a good weight, the odds are a heck of a lot better that you will not develop diabetes.  In essence, to a large degree you can control your destiny.  (There are, however, occasions where despite doing everything right, diabetes develops anyhow).

TYPE 1 OR TYPE 2 DIABETES & PREGNANCY

I would like to stress that gestational diabetes is an ENTIRELY DIFFERENT condition than is pregnancy in a woman with type 1 or type 2 diabetes.  The implications are vastly different as are the risks.  Mom's with GDM are NOT at higher risk of having a baby born with abnormal organs (so-called "congenital anomalies").  Nor, for that matter, are most moms with DM 1 or DM 2 if their sugar levels are excellent. BUT, if you have DM 1 or DM 2 with poor control during the first trimester (that is, the first several months of pregnancy) then, as demonstrated by the following table, the risks of having a baby with a major birth defect are much higher:

* Note that this table is based on the few medical studies available and the percents given should be considered as estimates.  The take home message is that the better your blood glucose control when you get pregnant and during the first few months of pregnancy (when the baby's organs are being formed) the less likely you are to have a baby with organ problems.

Please note that although these numbers are alarming, if you are pregnant and if your control has been poor there is still a good chance that your baby will be fine.

Poor control is also associated with a much higher rate of miscarriages:

If you have DM 1 or DM 2 and you want to get pregnant then do not even dream of doing so unless you have consulted with your health care providers and determined that your glucose control is acceptable to allow for a safe pregnancy (generally, that means excellent sugar levels with normal or nearly normal A1C's).  The other key things to be assessed prior to a woman with type 1 or type 2 diabetes getting pregnant are the health of the eyes (particularly the backs of the eyes called the retina) and the health of the kidneys since, if significant damage already exists, it can progress rapidly during pregnancy.  Now I don't want to sound alarmist.  I have looked after HUNDREDS of women with diabetes (both type 1 and type 2) who have had uneventful pregnancies and beautiful, healthy babies.  But it has to be a planned pregnancy and undertaken only after all appropriate precautions have been employed.

Another thing... You can further improve your odds of having a healthy baby if you take folic acid supplements before (and during) pregnancy.  The best dose is unknown but the Motherisk Clinic at Toronto's famed Hospital for Sick Children recommends a daily dose of 5 mg for women with type 1 or type 2 diabetes beginning 3 months before conception and taken until about 12 weeks into the pregnancy (at which time the dose can be reduced to between 0.4 and 1 mg per day which should be continued until you have completed breast feeding).  If you have type 1 or type 2 diabetes and are pregnant or considering pregnancy, be sure to speak to your doctor about folic acid supplements.

Can we prevent Type 1 diabetes?  Learn about the TRIGR study.

More information on diabetes and pregnancy.