Does anyone else think the traditional oral glucose tolerance test to screen for gestational diabetes, is enough to put anyone in to a diabetic coma? For regular healthy women who are conscious about what they eat, this test is highly inappropriate.
Let me explain why…
Firstly, let’s go over some basic physiology to understand how a healthy body deals with the breakdown of sugar (glucose). As glucose is ingested, blood glucose levels rise almost immediately. The pancreas responds by secreting insulin. Insulin helps the liver store excess glucose as glycogen until it is needed. As blood glucose levels begin to fall a few hours later, the stored glycogen is converted back to glucose to provide energy until more food can be eaten.
What many people don’t realize is that during pregnancy the placenta produces the hormones Lactogen, Estrogen and Progesterone, all of which counteract the function of insulin. The placenta also makes potent enzymes that destroy Insulin. Why would that be, I hear you ask. The body suppresses insulin purposely to allow more glucose to remain available in the mother’s bloodstream for longer periods of time. This is known as ‘glucose sparing’. Glucose sparing increases as pregnancy advances, peaking during the third trimester when the fetus gains most weight and needs more nourishment to grow. In other words, at 28 weeks (the time gestational diabetes screening is performed) the body actively creates higher levels of blood glucose (the very thing the test screens for) so that it is available for the baby to use to support its growth in the last trimester. In the medical field this is seen as a malfunction, a glucose ‘intolerance’, however this is normal pregnancy physiology.
For those of you who are not familiar, I will briefly explain the procedure of the oral glucose tolerance test (OGTT).
- A woman fasts for (at least) 8 hours before the test
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- Her fasting glucose level is taken via a blood sample to gain a baseline result
- She is given a sugary drink containing 100g of glucose (often with artificial colors and additives too) within 5 minutes
- Blood is taken at 1, 2 and 3 hour intervals after the drink is consumed
The problem with this test in women who don’t ordinarily ingest such high levels of glucose, is that their body is not used to handling the overload. The pancreas cannot produce sufficient quantities of insulin fast enough to meet the demand. Therefore levels become temporarily elevated until the pancreas has chance to catch up. This decreased carbohydrate tolerance is known as starvation diabetes. When the pancreas catches up with the glucose overload, insulin surges, and glucose levels plummet. This is called the rebound effect. This shock reaction is not true diabetes. A woman with a diet with a low intake of refined carbohydrates is at high risk of starvation diabetes.
Giving a woman a concentrated refined sugar load before testing is not recommended. She can have a physiological reaction to the glucose overload which can mimic diabetes. When the pancreas is presented with such high levels of glucose, not enough insulin can be produced fast enough to compensate. A temporary peudo-diabetes results, making results abnormally high. When the pancreas catches up insulin surges and blood glucose levels crash. This rebound effect actually mimics hypoglycemia. The period of time for this to occur varies, but often the 1-3 hour OGTT is not long enough to allow levels to come down to a normal baseline.
This test is bad enough to put the mother through, but think what effects this has on her unborn baby. Think carefully before willingly undergoing this seeming ‘harmless’ procedure.
Ask your health care provider for alternative screening methods.
