Understanding Gestational Diabetes

What is Diabetes?

Usually before becoming pregnant we know of Type-1 and Type-2 Diabetes Mellitus, however, we usually have not yet come across the term Gestational Diabetes, which is a condition that uniquely affects some pregnant women.

DM (Diabetes Mellitus) is primarily an insulin-level disease, as insulin is the hormone that facilitates our body’s cell tissue converting glucose (blood sugar) into energy.

Type-1 IDDM (Insulin Dependent Diabetes Mellitus) is when a person is born unable to produce normal insulin levels, and this is usually diagnosed during childhood or adolescence. IDDM is treated by supplementing the body’s insulin through tablets or injections.

Type-2 NIDDM (Non-Insulin Dependent Diabetes Mellitus) is typically associated with aging, due to inadequate levels of insulin production and/or increasing insulin resistance and/or Western lifestyle of very rich diets (now becoming more commonly diagnosed in younger generations due to childhood obesity).

But the big problem with Diabetic insulin imbalances, it is an escalating downward spiral: As cellular tissue becomes low in glucose energy, the body releases higher and higher levels of glucose sugar into the bloodstream to feed the “starving” cells. But it is not the lack of blood sugar that is the problem – the problem is the lack of insulin for cell tissue to convert the glucose into energy. This leads to worsening hyperglycaemia (high blood sugar) which can cause serious permanent damage to blood vessels.

Type-3 GDM (Gestational Diabetes Mellitus) is a unique phenomenon within the physiology of pregnancy:

Pregnancy hormones increase the mother’s insulin resistance, to boost energy available to the baby, resulting in the mother’s insulin levels doubling by the 3rd trimester. But, if the pregnant woman’s pancreas is unable to produce enough insulin to keep up with demand, then she will develop high blood sugar (hyperglycaemia) – and all its subsequent pathological complications.

Diagnosing & Treating GDM

Our renal kidneys filter (clean) our blood, excreting our urine as waste product, so an early sign can be detecting glucose in urine. This is because when our nephrons (kidney cells) are bombarded with sugar-rich hyperglycaemic blood, it damages their glomerulus capillaries allowing large glucose molecules to leak into the urine. Subsequently, midwives routinely ask pregnant women to do a urine dipstick test at each antenatal appointment.

Apart from Glucosuria (glucose sugar in the urine) other signs & symptoms of Diabetes Mellitus include:
 Fatigue, Weakness, Excessive hunger & Infection (all due to lack of energy)
 Large volumes of urine, intense thirst and dry itchy skin

As an extra double-check for undiagnosed Gestational Diabetes, at around 24-28 Weeks pregnant, midwives recommend to women a Polycose screening test for Diabetes. This screen takes one hour and includes a blood test on arrival, drinking a sugary drink and returning exactly an hour later for a second blood-test.

  • If the results come back with mildly elevated blood sugar levels, then it’s recommended the test is repeated in 3-4 weeks.
  • If the results come back with higher than normal levels, then it’s recommended a 12-hour fasting diagnostic GTT (Glucose Tolerance Test) is done.
  • If the results come back with very high blood sugar levels, or if the GTT test result is positive, then the LMC must recommend the woman receives a referral consult with the DIP Team (Diabetes in Pregnancy team).

The Diabetes in Pregnancy team will educate the woman on managing her blood sugar monitoring, including diet and exercise. Some GDM is able to be controlled through diet modifications alone, and some GDM becomes insulin-dependent (just while the woman is pregnant).

Diabetes Affects on Baby

Although maternal blood sugar crosses the placental barrier, insulin molecules do not, so all babies produce their own insulin for converting blood sugar into cellular energy. If maternal Diabetes Mellitus goes undetected or is poorly managed, then this will affect the baby including:

  • High levels of fetal insulin which inhibits lung maturity, leading to neonatal respiratory distress.
  • High levels of fetal insulin also act as a growth hormone, leading to fetal macrosomia (large cherub-like baby).
  • Macrosmic baby has increased risk of shoulder dystocia at birth (shoulders getting stuck after the head is born).
  • Macrosomic fetus has increased demands for oxygen, leading to fetal hypoxia and subsequent growth-restriction (small-for-dates baby).
  • Fetal hypoxia leads to ruddy-red baby with polycythaemia (increased red blood cells), which increases the risk of severe neonatal jaundice.
  • Large for dates uterus due to Polyhydramnios (excess amniotic fluid around baby from baby’s increased urinating) which has another whole set of additional potential complications.
  • And after birth, severe neonatal Hypoglycamia due to the baby’s insulin-rich blood loosing its supply of sugar-rich maternal blood, rapidly leading to dangerously low blood sugar levels.

All in all, quiet a can of worms – which is why signs and symptoms of GDM are so routinely monitored during pregnancy – because all pregnant women are at risk of Gestational Diabetes just from the fact of being pregnant.

The good news is that after childbirth the great majority of women’s bodies return totally back to their normal insulin and blood glucose levels. However due to an increased risk of Type-2 Diabetes later in life, a GTT test every couple of years is recommended.

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