What Is Diabetes?

Diabetes is a chronic condition that prevents the body from transforming food into energy. Our bodies normally convert food into sugar, or glucose, which cells absorb and turn into the energy they need to function. In diabetics, that absorption process is interrupted, causing sugar to build up in the blood.

The buildup of sugar in the bloodstream can cause serious damage to your cardiovascular system. The shortage of sugar in the rest of your cells reduces the amount of energy available to your body, leading to possible organ damage. Diabetes significantly increases your risk for heart disease by three to five times6  - in fact, 80% of all people with diabetes will die of either CVD or stroke.8 People with diabetes are also more likely to be overweight and have high blood pressure and high cholesterol, all of which are strongly linked to cardiovascular disease.

This increased risk is three times greater in women than in men. This is because women with diabetes are more likely to experience adverse changes that add to their risk for heart disease. They tend to have greater stores of belly fat and higher cholesterol and blood pressure levels. Men with diabetes experience some of the same effects but to a lesser degree. Also stacking the deck against women is the aging process. They lose estrogen, their natural protection against heart disease, at menopause.7

Everyone can benefit from cutting back on sugar, but the cause of diabetes is much more complicated than that: It’s a group of diseases with a range of causes, and it’s on the rise in many parts of Canada. Nine million Canadians have diabetes or pre-diabetes.1 Canadian adults with diabetes are twice as likely to die prematurely as those without diabetes, shortening their life expectancy by 10 to 15 years.

This video explains more about the health risks of diabetes (Health Design Lab).

How Does Diabetes Work?

Diabetes and your heartGenerally, the food you eat is turned into sugar, or glucose, that your body needs. Glucose is the body’s main source of energy. Blood glucose refers to the amount of sugar in your bloodstream.

When your blood glucose levels are too high, the pancreas (an organ located near your stomach) releases a hormone called insulin to stimulate your cells and liver to absorb glucose. This brings your blood glucose levels back to normal.

Diabetes keeps your body either from producing enough insulin or from using its own insulin as well as it should. This causes sugars to build up in your blood. High levels of sugar in your blood can increase the buildup of fatty deposits on blood vessel walls, narrowing the walls and reducing blood flow. Over time, these deposits may harden or clog the vessels, resulting in heart disease.

More detailed information about diabetes is available from My Favourite Medicine.

There are three main types of diabetes:

Type 1 Diabetes:

  • 5% to 10% of people with diabetes have type 1, the most severe type.
  • It usually develops in childhood or adolescence.
  • It is caused by a faulty immune response in which the immune system attacking and destroying part of its own pancreas.
  • Type 1 diabetes often requires lifelong insulin treatment.

Type 2 Diabetes:

  • 90% to 95% of people with diabetes have type 2, the most common form.
  • It usually affects adults.
  • The pancreas produces too little insulin or can’t use the insulin properly, which results in too much glucose building up in the blood.
  • It can be controlled through lifestyle changes and medications.

Gestational Diabetes Mellitus (GDM):

This type occurs during pregnancy from hormone changes and development of the fetus, which puts added demand on the body to produce sufficient insulin. GDM increases the risk for type 2 diabetes later in life; 30% of women with GDM will develop type 2 diabetes within 15 years. If appropriate steps are taken for control of blood glucose, a healthy delivery can be expected.


“Prediabetes” is considered more of a phase of diabetes than a type. If you are diagnosed with pre-diabetes by your doctor, this does not mean you have diabetes. It refers to blood glucose levels that are slightly out of range or higher than normal, but not enough to be considered diabetes mellitus.

Prediabetes is strongly related to the risk for type 2 diabetes and can be prevented or reversed by making lifestyle changes.

Who Is at Risk?

Type 1 diabetes is less common, and the risk for developing it usually stems from factors that are outside your control, such as environmental triggers or genetics, making it harder to prevent. The following factors increase your risk of developing Type 2 diabetes and Gestational Diabetes:

Risk Factors for Type 2 Diabetes:

  • Age (being 40 years or older)
  • Family history (having first-degree relatives with diabetes)
  • Ethnicity (being of Aboriginal, Hispanic, Asian, South Asian, or African descent)
  • Being obese or having an elevated waist circumference
  • Having a diagnosis of prediabetes or gestational diabetes, high blood pressure, high cholesterol, or schizophrenia

Risk Factors for Gestational Diabetes:

  • Age (being 35 years or older)
  • Ethnicity (being of Aboriginal, Hispanic, Asian, South Asian, or African descent)
  • Giving birth to a baby weighing more than 9 pounds
  • Being obese or having an elevated waist circumference
  • Having a diagnosis of gestational diabetes, polycystic ovary syndrome, or acanthosis nigricans (a skin disorder)
  • Using corticosteroids

To see whether you are at risk, take this diabetes questionnaire.

Healthy Targets for Blood Glucose

Blood glucose is measured in millimoles per litre (mmol/L).

People with diabetes have fewer complications when they consistently stay within their targeted blood glucose range. Healthy targets for people with and without diabetes are provided below.

  Target Blood Glucose Before a Meal Target Blood Glucose 1 Hour After a Meal Target Blood Glucose 2 Hours After a Meal Target Hb A1c
For people without diabetes 4.0-6.0 mmol/L   5.0-8.0 mmol/L 4.0-6.0%
For people with diagnosed diabetes 4.0-7.0 mmol/L   5.0-10.0 mmol/L ≤ 7.0%
For women who are pregnant 3.8-5.2 mmol/L 5.5-7.7 mmol/L 5.0-6.6 mmol/L ≤ 6.0%


What Are the Symptoms of Diabetes?

There may be no signs or symptoms. However, possible symptoms of the onset of type 2 diabetes include:

  • Unusual thirst
  • Frequent urination
  • Unexpected weight gain or loss)
  • Extreme fatigue
  • Low energy
  • Blurry vision
  • More frequent infections
  • Cuts or bruises that are slow to heal
  • Tingling and/or numbness in hands or feet
  • Erectile difficulties

Talk with your doctor right away if you are experiencing any symptoms you believe could be associated with diabetes.

How Is Diabetes Diagnosed?

There are three bloods tests that can help your doctor determine whether you have diabetes:

Fasting Plasma Glucose (FPG): FPG measures the amount of glucose in your blood while you are fasting. Fasting consists of not eating or drinking for at least eight to 10 hours before blood is drawn. Water is acceptable.

Random (non-fasting) Blood Glucose: Blood is drawn at any time of day without fasting.

Oral Glucose Tolerance Test (OGTT): This test allows for two blood samples to be drawn in a two-hour period. The first blood sample is taken immediately after consuming a sweetened drink. You then retake the blood test two hours later to determine whether diabetes is present.

The recommended screening test is the FPG, but a different test may be administered depending on other risk factors and any previous abnormal results.

If your doctor suspects diabetes after giving you the FPG, he or she will likely recommend the oral glucose tolerance test to confirm the diagnosis and determine the appropriate treatment. 


How Is Diabetes Treated?

Treatment will vary based on the type of diabetes you have, your risk factors for other conditions, and the test results. Normally, type 2 diabetes can be treated with lifestyle changes and these are important to controlling type 1 diabetes as well. In fact, lifestyle changes alone can reduce your risk of developing type 2 diabetes by as much as 60%. These changes in habits can also help reduce other risk factors, such as high blood pressure and cholesterol. But medications, particularly those targeted to risk factors, may still be necessary.10

 For detailed information on medication and lifestyle options, visit our Managing Your Diabetes page.

How Can I Reduce My Risk?

No one knows how to prevent type 1, but paying careful attention to your lifestyle choices can delay or lower your risk of developing all types of diabetes. Healthy eating, regular physical activity and weight control, as well as cholesterol and blood pressure management can all help to slow down or avoid the development of diabetes.

  • Eat well by following Canada’s Food Guide. This video explains how to manage your nutrition (Ontario Ministry of Health).
  • Enjoy regular physical activity. Getting at least 150 minutes each week will help keep your blood glucose within a healthy range and promote a healthy weight. Understand the warning signs of low blood glucose (pdf).
  • Achieve a healthy weight. Obesity is a leading cause of type 2 diabetes. Combining physical activity and a healthy diet is the best way to achieve a healthy body weight. In fact, reducing your body weight by 5% to 7% can prevent 58% to 71% cases of diabetes.11 This video explains how to manage your weight (Ontario Ministry of Health).

Whether you want to prevent diabetes or manage it, having healthy blood glucose levels can greatly improve your overall health and well-being. If you bring your blood glucose within the normal range, you are likely to have more energy, better manage your weight and improve your blood pressure and cholesterol levels.

In fact, effectively managing your blood glucose will help you lower your risk for other health complications, such as cardiovascular disease, stroke, blindness, and kidney disease. If you are already diagnosed and living with diabetes, better glucose management can potentially reduce the amount of medication and/or insulin you require.

Change is possible; hear Susan’s story, along with other real-life stories.

Managing Diabetes

Medication and Insulin Therapy

Regardless of your lifestyle, if you are diagnosed with type 1 diabetes, you will require treatment with insulin injections. There are four main types of insulin available. You will be prescribed insulin based on your lifestyle choices, including activity level and eating habits.8

The four types of insulin have different activation times following injection:

Long acting (basal insulin)

Intermediate acting (basal insulin)

Short acting (bolus insulin)

Very rapid acting (bolus insulin)

Each type takes effect at a different rate, peaks at a different time, and varies according to duration. This video presentation offers an overview of insulin (University of Ottawa Heart Institute), its role, side effects, and response time.

The Canadian Diabetes Association provides more information about diabetes products and medications.

Medication for Type 2 Diabetes

Type 2 diabetes can be treated with medication to help your body better control blood glucose. Some of the available brand and generic drugs are described in the chart below. Medication is usually started if two to three months of lifestyle management show little or no improvement in blood glucose levels.

Brand (generic)


When It Should Be Taken

Possible Side Effects

Diabeta (glyburide)

Diamicron (gliclazide)

Amaryl (glimepiride)





GlucoNorm (repaglinide)

Starlix (nateglinide)

Acts directly on pancreas

Stimulates release of insulin




Slows digestion of starches and sugars

Take immediately before, with, or immediately after eating a meal and never at bedtime



Take before each meal; do not take without food

Hypoglycemia, weight gain, rash, nausea, diarrhea





Hypoglycemia, weight gain, rash, nausea, diarrhea


Januvia (sitagliptin)





Onglyza (saxagliptin)






Trajenta (linagliptin)




Acts on gut and hormones when food is ingested

Suppresses glucose secretion from liver if blood sugar is high


Take 100 mg tablet once a day at any time but same time each day



Take 5 mg tablet once a day, same time each day




Take 5 mg tablet once a day with or without a meal

Stuffy nose, sore throat, rash, hives




Upper respiratory infection, urinary tract infection, headache, hives, rash


Cough, inflamed nose or throat, allergic reaction

Glucobay (acarbose)

Slows digestion of sugars


Hypoglycemia, severe gas, stomach pain/cramps, abdominal discomfort

Glucophage, Glumetza (metformin)







Actos (pioglitazone)





Avandia (rosiglitazone)






Helps insulin work better

Decreases sugar production by liver






Take 4 tablets a day with meals

Diarrhea, nausea, metallic taste, increased fertility

Not recommended for people with kidney disease, heart failure, or liver failure


Fluid retention, weight gain



Increased fractures, increased fertility

Not recommended for people with heart failure or liver failure

Victoza (liraglutide)


Byetta (exenatide)



Mimics action of hormones

Lowers blood glucose

Increases insulin release

Slows production of glucose in liver

Inject once a day


Inject twice a day, before breakfast and supper


Nausea, weight loss






This Heart Institute presentation offers an overview of type 2 diabetes medications.


If you have diabetes, it is important to take your medication and live a heart-healthy lifestyle. The following are tips to help you achieve this:

Take your medications as prescribed and learn more about managing your medications (Ontario Ministry of Health) with this video.

Learn about managing your diabetes by attending a diabetes education program.

Monitor and keep track of your blood sugar:

Target: Blood sugar before meals should be between 4 and 6 mmol/L.

Target: Blood sugar two hours after meals should be lower than 10 mmol/L.

Follow the Heart Healthy Nutrition Plan.

Be active every day. Being physically fit significantly decreases your risk for premature death.

Achieve and maintain a healthy body weight.

Ensure good foot health: Take care of your feet.

Visit your family doctor or diabetes specialist regularly.

It's natural to have questions about what food to eat. A registered dietitian can help personalize your meal plan. If you have diabetes and are taking insulin, speak with your family doctor. You may need to see an endocrinologist (a doctor who specializes in diabetes).

Monitoring Your Blood Glucose Levels

The most important thing about caring for yourself and managing your diabetes is self- testing your glucose levels. You will use a glucose monitor (glucometer) to do this. It will help you keep your levels within a healthy target range.

You can purchase a glucometer at any local pharmacy. Be sure to choose the one that’s right for you. Ask your pharmacist about choosing a glucose monitor.

Before you head home with your glucose monitor, be sure you understand how to use it.

This video can help you manage your blood glucose (Ontario Ministry of Health).

How Often Should You Test Your Blood Glucose?

Type 1 Diabetes:

At least three times a day with a glucometer

Measure before and after meals

Type 2 Diabetes:

At least once a day with a glucometer

Hemoglobin A1c (Hb A1c) is a test that provides an average of your blood glucose levels over a prior two- to four-month period. The result indicates how stable your blood glucose levels have been over time. It should be measured every three months. Talk to your doctor about requesting the blood work.

Gestational Diabetes:

Blood glucose should be measured with an oral glucose tolerance test at six weeks and at six months after giving birth.

When planning another pregnancy.

If diabetes is no longer present, then every three years (or more often, depending on other risk factors).11

Download the 2013 Canadian Diabetes Guidelines


1. Canadian Diabetes Association. www.diabetes.ca.

2. Vander AJ., Sherman JH., Luciano DS., : Physiologie humaine: les mécanismes du fonctionnement de l'organisme. 4th ed. Maloine E, ed. Juillet, 2004. Chenelière Mcgraw-Hill

3. Atlas of Cardiovascular Health in the Champlain Region 2011. Champlain Cardiovascular Disease Prevention Network, May 2011. http://www.ccpnetwork.ca/documents/Atlas2011FINAL.pdf

4. Stand Up to Diabetes. http://www.health.gov.on.ca/en/public/programs/diabetes/intro.

5. Champlain Diabetes Strategy. Ontario Local Health Integration Network, July 2009.

6. Lipid Clinic 2012, November 22, 2012. www.ottawaheart.ca/patients_family/lipid-clinic.htm.

7. Jaglal S, Slaughter PM. Risk factors for cardiovascular disease. In Cardiovascular Health and Services in Ontario. Toronto, Ontario, Institute for Clinical Evaluative Sciences, 1999:63-82.

8. Diabetes. University of Ottawa Heart Institute, 2012. http://www.ottawaheart.ca/heart_disease/diabetes.htm.

9. National Diabetes Education Program. http://ndep.nih.gov/am-i-at-risk/index.aspx.

10. Heart and Stroke Foundation. "Diabetes and you: manage your lifestyle. Reduce your risk." http://www.heartandstroke.com/site/c.ikIQLcMWJtE/b.5544357/k.7A75/Heart_disease__Diabetes_and_you_Manage_your_lifestyle_Reduce_your_risk.htm

11. Canadian Diabetes Association 2008 clinical practice guidelines for the prevention and management of diabetes in Canada. Canadian Journal of Diabetes. 2008; 32(1).