Islets of Langerhans

What is Diabetes

Diabetes mellitus is a disease characterized by abnormally high blood glucose levels – a condition called hyperglycemia.  This is a result of the body’s inability to regulate its fuel metabolism, and is usually related to the hormone insulin:

Type 1 diabetes – caused by insufficient insulin production.  Also called “insulin-dependent” diabetes because the only treatment is insulin replacement, or “juvenile” diabetes because the onset of type 1 diabetes usually occurs in juveniles and adolescents.  Type 1 makes up about 10% of all cases of diabetes.

Type 2 diabetes – caused by a reduction in the body’s response to insulin.  Also referred to as “insulin-independent” diabetes because insulin replacement is often not necessary,  or “adult-onset” diabetes because the onset of type 2 diabetes usually occurs in adults over 40.  In Type 2 diabetes, lack of response to insulin often leads to reduction of insulin production.  Type 2 diabetes makes up about 90% of all cases of diabetes.

Gestational diabetes – hyperglycemia that is first diagnosed during pregnancy.  Although this condition usually disappears after childbirth, women that had gestational diabetes are at risk of developing diabetes within 5 - 10 years after delivery.  Gestational diabetes occurs in about 4% of pregnancies in non-Aboriginal women, but occurs at a rate of up to 18% in Aboriginals.

What is insulin?

Insulin is a hormone – a chemical produced in one part of the body that travels to another location and signals it to perform an action.  In the case of insulin, this hormone is produced in beta (β) cells of a region of the pancreas called the “islets of Langerhans”.  Insulin released from β-cells travels to different organs in the body and signals the cells to uptake glucose from the bloodstream – by doing so, the level of glucose in the bloodstream drops.  Although the cells of some organs like the CNS and the liver don’t require insulin to uptake glucose, the majority of organs and tissues do.  Without sufficient insulin (Type 1 diabetes) or without sufficient response to insulin (Type 2 diabetes), glucose does not get transferred from the bloodstream to within cells, causing a hypergylcemic state.  In other words, despite abundant glucose in the body, it can’t make its way to where it’s needed the most – inside cells.

What is glucose?

Glucose, often referred to as “blood sugar”, is a simple sugar or carbohydrate.  Some foods we eat contain glucose, or they may contain other simple sugars and more complex carbohydrates that are converted to glucose by our bodies.  Excess glucose is often stored in our liver and muscles in a more compact form called glycogen, which can be mobilized back to glucose in the bloodstream if a person goes without eating for extended periods and their blood glucose level drops.  Smaller amounts of glycogen are stored in other cells.  Excess glucose can also be stored as fat. 

What is glucose used for in our bodies?

Glucose is an important source of energy in the body, along with fat and to a lesser extent, protein.  Every cell in your body requires energy to fuel the many reactions that go on constantly.  Many parts of your body can use both glucose and fatty acids (breakdown products of fat) to provide energy.  Surprisingly though, the central nervous system (CNS), which includes your brain, relies almost exclusively on a constant supply of glucose in the bloodstream and has little stored energy in the form of glycogen.  Fatty acids are unable to make their way to the CNS because of a physiological restriction called the blood-brain barrier, making the CNS more vulnerable than other organs.  Under extreme circumstances such as prolonged fasting, protein in your body can be broken down (proteolysis) and the amino acids converted to glucose in order to satisfy the energy needs of the CNS (gluconeogenesis).  However, bodily proteins make up crucial structural and functional bodily constituents such as enzymes, contractile proteins, and nervous tissue; therefore, utilizing these as an energy source is the body’s last resort.  

What happens when there is too little glucose in our blood?

During short-term fasting or even during strenuous exercise when blood glucose falls (hypoglycemia), the body will convert glycogen stores in liver and muscle to glucose which enters the bloodstream (glycogenolysis).  Fatty acids can also be readily used by most organs for fuel, alongside glucose – again, with the exception of the CNS.  After prolonged fasting or starvation where glycogen stores start to become depleted, the body increasingly relies on fatty acids derived from fat stores for fuel (lypolysis).  In the case of the CNS, the body can adapt to this state somewhat by converting fatty acids to compounds called  ketone bodies that are able to cross the blood-brain barrier, reach the cells of the CNS and serve as a source of energy (ketogenesis).  Normally ketone bodies play little role in normal body metabolism, but the body’s ability to create these compounds is an important defence mechanism against CNS vulnerability during starvation.  However, relying too heavily on ketone bodies for prolonged periods poses its own health risk.  Also, as fat stores become depleted, the body starts switching to protein breakdown for energy, which ultimately has dire consequences on bodily structure and function.

What happens if I have diabetes and what are the associated health effects?

With untreated diabetes, some of the consequences that can arise are the same as if you were starving.  Because of insufficient insulin, or insufficient response to insulin, glucose does get transported from blood to inside cells to give them energy.  Therefore, regardless if a diabetic is fed and blood glucose levels are normal or even high, the body will sense that more glucose is needed and will respond the same as if you were in a fasting or starving state: glycogenolysis, lipolysis, ketogenesis, proteolysis and gluconeogenesis.  This will lead to increased hyperglycemia and an unnecessary breakdown or catabolic state.  The body will compensate by excreting glucose in the urine, thereby exhausting glycogen stores despite an abundance of glucose.  In the case of untreated diabetes and fasting, catabolism, gluconeogenesis and ketogenesis can become greatly increased, leading to profound hyperglycemia and excessive levels of ketones in the blood (hyperketonemia), which can lead to a life-threatening alteration of blood acidity (ketoacidosis).  In addition to all this, chronic hyperglycemia has a direct, toxic effects on cells (glucose toxicity), including both the development of insulin resistance in peripheral cells and impaired insulin secretion from β-cells.  Insulin impairment is also associated with altered metabolism of ingested proteins and fat, resulting in higher than normal levels of circulating amino acids and triglycerides.

Over time, poorly or unmanaged diabetes is strongly associated with numerous health risks and secondary complications:

  • Life expectancy for people with type 1 diabetes may be shortened by as much as 15 years. Life expectancy for people with type 2 diabetes may be shortened by 5 to 10 years
  • About 80% of people with diabetes will die as a result of heart disease or stroke
  • Canadian adults with diabetes are twice as likely to die prematurely, compared to people without
  • Secondary complications related to diabetes include cardiovascular disease, nerve damage, vision impairment and kidney disease.  For a more comprehensive description, please refer to the following link on the Canadian Diabetes Association website.
  • For women with gestational diabetes, children born may have large birth weights, which in turn is associated with higher rates of cesarian deliveries.  These babies also risk dangerously low blood sugar levels following birth and excess levels of insulin in the blood.  Children of mothers that experienced gestational diabetes are also at a higher risk for obesity later in life; the mothers themselves are at higher risk of developing type 2 diabetes.

What causes diabetes?

  • Type 1 diabetes is an autoimmune disease.  Normally a person’s immune system is programmed to recognize and attack foreign particles, microbes and cells, but in cases of autoimmunity the immune system somehow loses the ability to differentiate foreign from self and attacks the host’s own tissues or cells.  In the case of type 1 diabetics, a person’s immune system triggers an immune reaction against islet cells, ultimately destroying them.  The factors that contribute to autoimmune diseases are not completely known, but genetic predisposition and geographic location play a role.  Type 1 diabetes often develops early in life.
  • Type 2 diabetes is a result of insufficient insulin production from the islets in the pancreas, or insufficient response or sensitivity to insulin (insulin resistance).  There are several risk factors associated with developing type 2 diabetes:
    • Obesity (body mass index, BMI>30 kg/m2) – 90% of type 2 diabetics are obese
    • High blood pressure
    • High cholesterol
    • Ethnicity (Aboriginal, Hispanic, Asian, or African descents are at higher risk)
    • Family history of type 2 diabetes
    • History of gestational diabetes
    • History of polycystic ovary syndrome
    • Schizophrenia.
  • Gestational diabetes can result from hormonal imbalances that can occur during pregnancy, which in turn can alter cellular sensitivity to insulin.  There are a number of risk factors associated with developing gestational diabetes, some similar to type 2:
  • Obesity (a pre-pregnancy BMI over 30 kg/m2)
  • High blood pressure
  • Ethnicity (Aboriginal, Hispanic, Asian, or African descents are at higher risk)
  • Family history of diabetes
  • Previous history of gestational diabetes
  • Unexplained stillbirth
  • Previous delivery of large baby, >4,000 gms (8 lbs 13 oz.)
  • Over 35 years of age

What are the prevalence, cost and trend of diabetes? 

  • Latest figures from the World Health Organization indicate 346 million people worldwide have diabetes – about 1 in 20 people
  • In Canada there are about 3 million people with diabetes or nearly 1 in 10 people, roughly the same ratio as in the US
  • A person with diabetes can face direct costs for medication and supplies ranging from $1,000 to $15,000 a year
  • By 2016, it’s estimated that diabetes will directly cost the Canadian healthcare system $8 billion a year – indirect costs will contribute just as much

How can the onset of type 2 diabetes be prevented or managed?

  • Achieve and maintain healthy body weight and BMI (see BMI calculator)
  • Engage in regular, moderate intensity physical activity for at least 30 minutes per day (more may be necessary for losing weight)
  • Eat a healthy diet of between three and five servings of fruit and vegetables a day and reduce sugar and saturated fats intake;
  • Avoid tobacco use – smoking increases the risk of cardiovascular diseases
  • Medications (see below)

    How can the onset of gestational diabetes be prevented or managed?

    Similar to preventing or managing type 2 diabetes, in most cases pregnant women can maintain normal blood glucose levels through healthy eating and regular exercise.  In extreme cases where blood glucose levels cannot be successfully managed with these efforts, women with gestational diabetes may need insulin injections.

    What is prediabetes?

    Prediabetes is a condition where you have higher than normal blood glucose levels, but not high enough to fall within the formal definition of diabetes (see below).  People who develop type 2 diabetes are likely to go through a pre-diabetes phase first; therefore, if diagnosed, pre-diabetes is an opportunity for intervention steps that can delay or even stop the onset of type 2 diabetes.

    How to determine whether you have diabetes, prediabetes or neither

    Talk to your family doctor – they can prescribe tests and determine whether a patient has normal metabolism, has prediabetes or diabetes using one of the following standard tests (source: Canadian Diabetes Association):

     

    • The HbA1C test - more than 6.4%:  diabetes - between 5.7% and 6.4% : prediabetes - less than 5.7% :  normal
    • The FPG (fasting plasma glucose) test - more than 6.9 mmol/l (124 mg/dl): diabetes - between 5.5 mmol/l (99 mg/dl) and 6.9 mmol/l (124 mg/dl) : prediabetes - less than 5.5 mmol/l (99 mg/dl) : normal
    • The OGTT (oral glucose tolerance test – after 2 hours) - more than 11.0 mmol/l (198 mg/dl): diabetes - between 7.8 and 11.0 mmol/l (141 and 198 mg/dl) : prediabetes - less than 7.8 mmol/l (141 mg/dl) : normal

    How to determine whether you have gestational diabetes

    Your physician will normally prescribe similar tests as above to screen for gestational diabetes, usually between 24 and 28 weeks, with the following as an assessment guideline (source: Canadian Diabetes Association):

    • The HbA1C test - 6.1% or more:  gestational diabetes - 6.0% or less:  normal
    • The FPG (fasting plasma glucose) test - more than 5.2 mmol/l (94 mg/dl): gestational diabetes - between 3.8 mmol/l (68 mg/dl) and 5.2 mmol/l (94 mg/dl) : normal
    • The OGTT (oral glucose tolerance test – after 1 hours) - more than 10.2 mmol/l (184 mg/dl) or more: gestational diabetes - 10.2 mmol/l (184 mg/dl) or less: normal

    How is diabetes treated?

    • Education: Diabetes education is an important first step. All people with diabetes need to be informed about their condition.
    • Physical Activity: Regular physical activity helps your body lower blood glucose levels, promotes weight loss, reduces stress and enhances overall fitness.
    • Nutrition: Eating the right types and amounts of foods in very important in managing blood glucose levels
    • Weight Management: Maintaining a healthy weight is critical for management of type 2 diabetes.
    • Medical Therapy: type 1 diabetes is either treated with insulin injections or with cell replacement therapy (Clinical Islet Transplant Program), which can lessen or even reduce the dependency on injections.  Type 2 diabetes is managed through physical activity and meal planning and may require medications and/or insulin to assist your body in controlling blood glucose more effectively.
    • Blood Pressure: High blood pressure can lead to eye disease, heart disease, stroke and kidney disease, so people with diabetes should try to maintain a blood pressure level at or below 130/80. To do this, you may need to change your eating and physical activity habits and/or take medication.

    Who can I turn to for help?

    The following link will be helpful in locating a diabetes education centre nearest you:  

    Diabetes Education Centre