Why does diabetes in pregnancy occur and does it matter?

As a baby grows in the womb, a mother’s body releases many different hormones, proteins and other chemical signals… it’s a crazy time! But it’s important to understand how lifestyle choices, such as diet, can influence both the mother’s and baby’s health.

As pregnancy progresses to the end second trimester and into the third, the mother’s body continues to change, her stomach and breasts increases in size, her hips widen as the baby continues to grow and develop.

What is impaired glucose tolerance?

Apart from the obvious, there are further unseen changes that occur in her body. The placenta, an organ that acts as the unborn child’s food source, releases signals known to influence the type of fuel (food) reaching the baby. Placental hormones, along with others released by the mother’s fat cells, cause the mother to become somewhat insulin resistant in the stages of pregnancy. This basically means the mother’s muscle cells do not respond to the insulin she has released, and consequently, she has difficulty using sugar from her blood. This is known as impaired glucose tolerance.

Why do women become insulin resistant in pregnancy?

But hang on, isn’t insulin resistance and impaired glucose tolerance related to diabetes? Why does a perfectly healthy pregnant women have insulin resistance?

…Because our bodies are clever and have learned to adapt!

Insulin resistance is actually an ancient survival mechanism. Our bodies have evolved to enable the mother to protect herself and her unborn baby during periods of fasting, when food was not plentiful. Insulin resistance allows the mother to use her fat stores as a source of fuel, by blocking her muscle cells from absorbing sugar, and spares the carbohydrate (sugar) for the rapidly growing unborn baby.

Unfortunately, in our modern world, there is usually too much food around. Mother’s tend to have plenty of fat stored in their cells, and are able to access adequate, or often, too much food during pregnancy. Excess fat, particularly around the stomach, combined with genetics puts the expectant mother at a greater risk of troublesome insulin resistance. Adding to this, women are generally waiting until later in life before becoming pregnant, which can amplify the effect of pregnancy insulin resistance. Insulin resistance in this instance can cause blood glucose levels to rise above normal, known as gestational diabetes (pregnancy diabetes).

The medical and scientific community are well aware that increased body fat, genetics and age are the biggest risk factors for gestational diabetes (A Prospective Study of Pregravid Determinants of Gestational Diabetes Mellitus). So, ensuring that the mother is in good health before pregnancy and is receiving nutrition and health advice from a qualified health care team is paramount to reducing the risk of developing gestational diabetes.

To the point:

  • Insulin resistance happens to some extent, in all pregnancies. It’s a survival mechanism to help the unborn baby to continue to grow in times where there are limited food sources.

  • Increased fat (particularly around the tummy) causes an increase in insulin resistance in pregnancy, this is further amplified by age and genetics.

  • Insulin resistance can cause increase blood glucose levels above normal values known as gestational diabetes.

Please see the following articles for more information: