Insulin for gestational diabetes

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Insulin for gestational diabetes


Insulin normally is made by the pancreas, a gland behind the stomach. The medication form of insulin helps the body use glucose. Insulin cannot be taken as a pill, because stomach acid destroys insulin before it can enter the blood.

Insulin is categorized according to how fast it starts to work and how long it continues to work. The types of insulin available include rapid-, short-, intermediate-, and long-acting insulin. See types of insulin for more information.


Insulin is packaged in small glass bottles that are sealed with rubber lids. One bottle holds 1,000 units, which is many doses of insulin. It is also packaged in small cartridges used in pen-shaped devices (insulin pens) attached to disposable needles. Insulin bottles and cartridges are labelled with important information you should read, such as the expiration date.

How insulin is taken

Insulin usually is given as a shot under the skin. Some insulins can be given in a vein, but this is only done in a hospital.

How It Works

Insulin reduces blood sugar levels by helping sugar (glucose) enter the cells to be used for energy. Sometimes women who have gestational diabetes need to take two types of insulin, usually a rapid- or short-acting and an intermediate-acting type. Long-acting insulins have not proved to be safe for use during pregnancy.

  • The short-acting insulin reduces blood sugar levels quickly and then wears off.
  • Some long-acting insulins start taking effect when rapid- or short-acting insulins begin to wear off.
  • The combination of a rapid- or short-acting and intermediate- or long-acting insulin helps keep blood sugar levels within a target range both before and after meals.

Why It Is Used

You will need to take insulin if changing the way you eat and getting regular exercise do not keep your blood sugar within a target range. Keeping your blood sugar within a target range is the best way to prevent problems from gestational diabetes, such as a baby who grows too large or a baby who is born with low blood sugar. Usually, gestational diabetes goes away after your baby is born. Then insulin is no longer needed.

People who have type 1 diabetes and some people who have type 2 diabetes also need to take insulin. For information on insulin for these types of diabetes, see the topics Type 1 Diabetes and Type 2 Diabetes.

How Well It Works

Currently, insulin is the only medicine that is approved by Health Canada to treat women who have gestational diabetes.

Side Effects

The major side effect of insulin can be low blood sugar (hypoglycemia). Very low blood sugar level can develop quickly (within 10 to 15 minutes). Low blood sugar can occur if you:

  • Take too much insulin or if insulin is injected into a muscle instead of into fatty tissue.
  • Skip or delay a meal or snack.
  • Exercise too much without eating enough food.
  • Drink alcohol, especially on an empty stomach. No amount of alcohol is considered safe to drink while you are pregnant.
  • Take certain medicines that can lower blood sugar. Some medicines that you can buy without a prescription can affect blood sugar levels. Talk with your doctor about all your medicines and their possible effect on blood sugar.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

What you need to know

Insulin treatment must fit your needs. Some factors that affect how fast and how well your insulin works include:

  • Where the dose is given. If insulin is injected into a muscle instead of into fatty tissue, the medicine will get into your system faster.
  • How much insulin is given. Higher doses of insulin reduce the blood sugar level more than lower doses.
  • What types of insulin are mixed together. Insulin's effects are felt more quickly when rapid-acting insulins are used alone.
  • Whether you have exercised before or just after taking insulin. If you have just exercised the muscles in the area where you give your insulin injection, the medicine will get into your system faster.
  • If you apply heat to the area. The medicine will get into your system more quickly if you put a heat pack on or massage the area where you have just given your insulin injection.

Things to check

Women who have gestational diabetes usually need to test their blood sugar level up to 6 times each day (before each meal and 1 hour after each meal).

A bottle of insulin may not work well after 30 days. Label each insulin bottle the first time you use it. Then, after 30 days, throw away any insulin you did not use from that bottle.

Always check the expiration date on the bottle.

Insulin should be stored properly. If it is not, it may break down and not work very well.

How to give insulin

To learn how to prepare and give insulin injections, see:

Click here to view an Actionset. Gestational diabetes: Giving yourself insulin shots.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.


By Healthwise Staff
Primary Medical Reviewer Anne C. Poinier, MD - Internal Medicine
Specialist Medical Reviewer Alan C. Dalkin, MD - Endocrinology
Specialist Medical Reviewer Donald Sproule, MD, CM, CCFP, FCFP - Family Medicine
Last Revised February 10, 2010

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.