Over 2 million Canadians have diabetes. There are three main forms of this condition.

Type I:  This occurs when the body fails to produce insulin.  As insulin is required to control (lower) the blood glucose by making it available for metabolism, a lack of insulin allows the glucose to rise to uncontrolled levels.  Ironically, though the blood has too much glucose, the tissues do not have enough and they begin to metabolize fat in order to get energy.  This results in the production of ketones that cause a metabolic crises and even death.  Insulin injections are required for treatment.

Type II:  Most people with diabetes have this form.  This is the variety developed later in life that was formerly called “adult onset” diabetes.  In Type II the body can still produce insulin but it either does not produce enough or the insulin it does produce is not used by the tissues. The result is  ineffective utilization of glucose that rises to elevated levels in the blood stream.  It can often be treated by diet and weight loss to reduce the demand for insulin, but treatment with insulin may be required.

The third type of diabetes is a temporary situation that occurs in pregnancy.  It is found in 2-4% of all pregnancies and poses a risk to the well being of the fetus.  It is standard practice to screen for the presence of this condition in all pregnancies.

The symptoms of diabetes vary.  Some persons with Type II or Gestational diabetes have no symptoms at all but are still at risk from the long-term complications of the disorder. When the symptoms become overt, the patient feels unwell, is very thirsty, excretes abnormally large volumes of urine, experiences unexplained weight loss, and may suffer serious metabolic derangement.

The diagnosis of diabetes is confirmed with laboratory tests.  Screening for diabetes is recommended every three years after the age of 45. There are new criteria for its diagnosis which are published in the CMA Clinical Practice Guideline for Diabetes.

Criteria

A patient with metabolic decompensation and unequivocal hyperglycemia may be diagnosed as diabetic with a single glucose measurement.  All other patients must have two venous plasma glucose measurements that exceed the following criteria:

Symptoms of diabetes plus a casual plasma glucose value ³ 11.1 mmol/L

OR

A fasting plasma glucose ³ 7.0 mmol/L

OR

A plasma glucose value in the 2-hour sample of the oral glucose tolerance test ³ 11.1 mmol/L

Category
 Fasting glucose (mmol/L)
 Glucose (mmol/L) 1-hour after drinking a 75 gram glucose drink
 Glucose (mmol/L) 2-hours after drinking a 75 gram glucose drink
 
Impaired fasting glucose
 6.1 – 6.9
 Not applicable
 Not applicable
 
Impaired glucose tolerance
 < 7.0
 Not applicable
 7.8 – 11.0
 
Diabetes mellitus
 ³ 7.0
 Not applicable
 ³ 11.1
 
Gestational diabetes
 ³ 5.3
 ³ 10.6
 ³ 8.9
 

To diagnose Gestational diabetes, all pregnant women over 25 years of age and all women under 25 who are overweight or who have risk factors should undergo a Gestational Diabetes Screening Test between 24 and 28 weeks’ gestation.  This is done using a 50-gram glucose drink.  If the level of glucose 1-hour later is ³ 7.8 a glucose tolerance test should be carried out.  If the level at 1-hour is ³ 10.3 then Gestational Diabetes is diagnosed and no further testing is needed.  When the oral Glucose Tolerance test is given and one value exceeds any of the limits listed below, Gestational Diabetes is diagnosed.  A physician may elect to treat a patient as a diabetic if the values get close to these limits.

Fasting > 5.3 mmol/L
 
1-hour post drink
 > 10.6 mmol/L
 
2-hour post drink
 > 8.9 mmol/L
 

Monitoring Diabetes

Once diabetes is diagnosed, therapy will be instituted. Most monitoring of insulin therapy is carried out by the patient who uses a glucose meter. There are two additional tests that are then recommended to be carried out in all Type I and Type II diabetics on a regular basis.

Glycated Hemoglobin

The Glycated Hemoglobin test (also known as Hemoglobin A1c  or Hb A1c) should be carried out every three to four months.  In this test, blood is drawn and analyzed for the amount of glucose that has become attached to the hemoglobin molecule.  Normally, not more than 6 % of Hemoglobin molecules have glucose attached to them.  Diabetics will have larger percentages.  The percentage is related to the “average” blood glucose level and is therefore an indication of overall glucose control. It should be noted that the percentage is reported not as a percentage but as a function of 1.0 (e.g. 6.0 % will be reported as 0.06).  If the Glycated Hemoglobin result is too high, more stringent insulin therapy is required. The Glycated Hemoglobin test should not be used for the diagnosis of diabetes as there are no recognized standards for using it in this context.

Glycated Hb
 Interpretation
 
0.04 – 0.06
 Ideal (normal non-diabetic)
 
< 0.07
 Optimal target zone for diabetics
 
0.07 – 0.084
 Suboptimal- action may be required
 
> 0.084
 Inadequate control: action required
 

Microalbumin

The other monitoring test is urinary microalbumin. This is carried out on an annual basis on a random urine sample in Type I patients over 15 years of age who have had diabetes for 5 years or more and in all Type II patients.  The lab measures the amount of the protein “albumin” in the sample. The result is expressed as a ratio compared to creatinine (a substance excreted in a constant amount). If the albumin rises above a critical level (2.8 or more in females and 2.0 in males), further testing is carried out to confirm that microalbuminuria is present.  This indicates that the diabetes is beginning to affect the kidney and therapy to prevent the rapid development of  kidney problems should be instituted.

Useful information about diabetes can be obtained from the website of the Canadian Diabetes Association http://www.diabetes.ca.