Gestational diabetes is a form of diabetes that occurs only during pregnancy, though it does increase your risk of T2D and gestational diabetes may be the result of a pre-existing undiagnosed diabetes.
Gestational diabetes is usually diagnosed in the later parts of pregnancy, and, like the other forms of diabetes, indicates that your blood sugar (blood glucose) is not being adequately regulated. It is important to diagnose and treat gestational diabetes because it can put you and your baby at risk for future diabetes. It also puts your baby at risk for having a condition called macrosomia—where the baby is born with a large body which can make delivery dangerous and difficult. Gestational diabetes also puts your baby at risk for early death, low blood sugar, jaundice (a liver condition) and respiratory distress syndrome.  Finally, having untreated gestational diabetes puts you and your baby at a higher risk of obesity.
Like other forms of diabetes, gestational diabetes can reflect insulin resistance, not enough insulin or the inability of your body cells to respond properly to the signals from insulin. In addition, the placenta (which connects your baby to your blood supply) can produce hormones which block the action of insulin. Insulin is a hormone produced by the pancreas—insulin signals the cells to take up glucose from the blood. All cells in the body use glucose (sugar) for energy, but as with most things, too much of any substance can be detrimental—and too much glucose in the blood for any length of time can damage the nerves, the kidneys, the eyes and other organs as well as put you at risk for heart disease, stroke and obesity.1
If you already have diabetes (either T1D or T2D) and are interested in having a baby, this can usually be done as long as your diabetes is being treated.
What are the Risk Factors for Gestational Diabetes?
The chances of gestational diabetes are higher if any one or more of the following apply to you.
- Obesity or being overweight
- A personal or family history of any form of diabetes
- A history of having given birth to a baby weighing more than 9 pounds
- A history of a hormonal condition known as Polycystic ovary syndrome, or PCOS
- An African, Native American, Hispanic, Asian or Pacific Islander ethnic background
How is Gestational Diabetes Diagnosed?
Your obstetrician will likely test your blood for signs of gestational diabetes (higher than normal blood sugar levels) between 24-28 weeks of pregnancy. This blood test may be done sooner if you have any of the risk factors for gestational diabetes. The blood test may be a fasting glucose test where you have no food for 12 hours before you blood is drawn. It may also consist of a glucose challenge test where you drink a sweet glucose solution and have your blood tested 1-2 hours later.
If you are diagnosed with gestational diabetes, you will likely require extra tests during pregnancy including Ultrasound (US) imaging, have your baby’s heart rate monitored regularly and possibly be screened for conditions such as pre-eclampsia, a condition that can be associated with gestational diabetes. Gestational diabetes can also increase your risk of high blood pressure—this in turn can put you at a higher risk for preeclampsia. For women who are able to control their gestational diabetes, fewer than 25% develop T2D in the future.3
How is Gestational Diabetes Treated?
Gestational diabetes is usually treated with a combination of a healthy eating plan; monitoring your blood sugar in the morning, before and after meals; and by increasing your physical activity level—since every cell in your body uses glucose for energy, exercising can help lower blood sugar levels. Some women may require insulin shots to keep the blood sugar levels within healthy limits. Medications other than insulin are generally avoided, though some doctors do prescribe blood sugar lowering medications. In addition, your baby’s growth and development will be even more carefully monitored—if the baby is growing too large, labor may be induced early or you may need to undergo a cesarean section to deliver.
Healthy eating focuses on complex carbohydrates (that release sugars more slowly), lots of vegetables and fruit. Complex carbohydrate foods include whole grains, beans, legumes and starchy vegetables. Sweets and simple carbohydrates (processed foods, fast foods and non-whole grain baked goods) are completely avoided.
Exercise can include simply walking, doing yoga or tai chi or swimming. It can also include using an elliptical or a stationary bicycle. Finally, housework and gardening count as exercise too!
Preventing Gestational Diabetes
The best treatment is always prevention. While there are never 100% guarantees, you can help prevent gestational diabetes and T2D before and during pregnancy by: 
- Losing any extra weight before you get pregnant
- Maintain a healthy diet before, during and after pregnancy.
- This will also help your baby develop healthy eating habits and if you breastfeed your baby, provide him or her with the best possible nutritional start in life!
- Keep physically fit and active
If you have further questions ask in the comment section.