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Gestational Diabetes (GDM)

Please refer to your program's policies and procedures when caring for women with diabetes in pregnancy.
The following information is meant to guide current and new staff of Calgary Diabetes in Pregnancy Clinics. For referral information please visit our Calgary Diabetes Services page.

1. What is Gestational Diabetes (GDM)? 


Gestational Diabetes Mellitus or GDM is defined as diabetes first diagnosed during pregnancy. Click here for a quick overview and video ( 

  • It is often helpful for new educators to listen to experienced educators explain GDM to patients. You can also refer to the GDM patient handout available on our topics catalogue. 
  • The term IGT (Impaired Glucose Tolerance) of Pregnancy should no longer be used as it was eliminated in the 2013 Clinical Practice Guidelines. There is no longer a diagnostic distinction between IGT and GDM.
  • Distinguishing GDM from Overt Diabetes: There is general acceptance of the following suggested guideline from the International Association of Diabetes and Pregnancy Study Groups (IADPSG): Overt diabetes can be diagnosed during pregnancy if fasting blood glucose > 7.0 mmol/L on a venous blood sample and/or A1C  > 6.5%. In this case, the client will retain the diagnosis of diabetes after childbirth. Research is currently looking at the appropriateness of these cut offs and method of diagnosis.

Educators are encouraged to study and/or view the following: 

  • Diabetes Canada's 2018 Clinical Practice Guidelines, Chapter 36: Diabetes and Pregnancy (explains screening, diagnosis, glycemic targets and medical management). 
  • AHS employees can request the following article from Knowledge Resource Service: Management of Diabetes in Pregnancy: Challenges and Trends by Sara Meltzer (Canadian Journal of Diabetes. 2005;29(3):246-256). 

2. How Do We Help Patients Manage GDM? 

A woman is referred to a Calgary Diabetes in Pregnancy Clinic after gestational screening is complete and she has screened positive or is diagnostic for GDM. She will be offered to attend a group Zoom class with other women who have also been diagnosed with GDM (or a 1:1 appointment with an educator if there are language or other barriers). She will be encouraged to visit our patient website to learn about GDM prior to the appointment or class. Imagine you are a patient and visit our website here ( to learn more.

The initial class or appointment will teach the following: 

Subsequent follow-up appointments with a diabetes educator will determine whether lifestyle management is helping to keep glucose levels in target. If glucose levels cannot be controlled with lifestyle measures alone, the patient may be assessed by a Diabetes in Pregnancy endocrinologist who may initiate Metformin or insulin. 

Calgary Diabetes in Pregnancy Clinics do not routinely ask women with GDM to check urine ketones. Starvation ketosis may have detrimental effects on the fetus. For this reason, management of GDM patients should emphasize importance of adequate nutrition in pregnancy. Caloric restriction to avoid insulin in GDM clients is not recommended. Refer to Nutrition Services- Nutrition Guidelines for Diabetes in Pregnancy.