a single occasion is not enough to make a diagnosis of diabetes (although important exceptions exist, which we discuss next). Any one of the tests must be also be positive on another day to establish the diagnosis. Also, the diagnosis of diabetes should be based on a blood sample taken from a vein and analyzed at a laboratory; the diagnosis should not be made based on a blood glucose level measured with a blood glucose meter.
✔ If your initial blood glucose level is 11.1mmol/L or higher and you have symptoms of high blood glucose (frequent urination, increased thirst, loss of weight)
✔ If your doctor thinks you may have type 1 diabetes (especially if you are a child)
In either of these circumstances, the diagnosis of diabetes is made without a second test, and you need to start treatment immediately.
Looking at Target Blood Glucose Levels
You can drastically reduce your risk of developing many types of diabetes complications by keeping your blood glucose levels in check. The Canadian Diabetes Association (CDA) has established these target blood glucose levels for most adults living with diabetes:
✔ Blood glucose before meals: 4.0 to 7.0mmol/L
✔ Blood glucose two hours after meals: 5.0 to 10.0mmol/L (5.0 to 8.0 if your A1C is above 7.0)
The A1C is an important test to determine whether your blood glucose control is where it should be. The A1C, which is performed on a blood sample taken from a vein in your arm at the lab, and should be done about every three months or so, reflects your overall blood glucose levels over the preceding several months. It uses a different scale from the usual blood glucose test, and the target value is 7 percent or less for most adults with diabetes.
Although the preceding blood glucose targets are appropriate for the great majority of adults, targets differ for elderly infirm or frail individuals, and for people with a limited life expectancy. In these circumstances targets are:
✔ Blood glucose before meals: 5.0 to 12.0mmol/L.
✔ A1C up to 8.5 percent.
You can learn more about the A1C on Ian’s website (www.ourdiabetes.com/key-definitions.htm).
Understanding How High and Low Blood Glucose Can Make You Feel
Having diabetes means that you will be prone to higher than normal blood glucose levels. Popular wisdom to the contrary, diabetes does not, in fact, cause low blood glucose; rather, it is certain drugs used to treat diabetes that sometimes leads to this. In this section, we look at how high or low blood glucose levels can make you feel.
High blood glucose is not an “all or none,” yes or no kind of thing. Rather, elevated blood glucose levels run a continuum ranging from only slightly higher than normal to up into the stratosphere. A person without diabetes seldom has blood glucose levels higher than 8mmol/L or so, and symptoms of high blood glucose develop only if blood glucose is higher than 10mmol/L or so.
Looking at the symptoms of high blood glucose
These are the most common symptoms of high blood glucose:
✔ Frequent urination
✔ Increased thirst
✔ Blurred vision
✔ Fatigue
✔ Hunger
✔ Weight loss
✔ Persistent vaginal infections
Not everyone with high blood glucose experiences all these symptoms. Indeed, many people have only one or two of these symptoms and some people have none at all. Also, the severity of the symptoms can vary widely. Some people have profound thirst, are running to the bathroom 24/7, and lose many pounds, whereas other people feel slightly tired and that’s it.
The fact that symptoms can be minimal or nonexistent partly explains why so many people with diabetes don’t know they have it. After all, if you feel perfectly fine it only makes sense you won’t suspect you’ve got a problem and thus won’t be knocking on your doctor’s door to get checked out.
Considering the complications of high blood glucose
Having high blood glucose can do two main things: It can cause symptoms like those we discuss in the previous section, and, if severe or if longstanding, it can damage the body.
If your blood glucose levels exceed target year after year, you will be at risk of a number of different types of complications. But if you keep most of your blood glucose levels within target you can dramatically reduce your risk of running into problems. In other words, diabetes complications are not inevitable!
Chronically elevated blood glucose levels can lead to complications like these:
✔ Eye damage (retinopathy), which, if severe, can lead to blindness
✔ Kidney damage (nephropathy), which, if severe, can lead to kidney failure and the need for dialysis
✔ Nerve damage (neuropathy), including abnormal or loss of sensation in the feet, which can be a factor leading to amputation
The role of high blood glucose in causing heart attacks and strokes is more complicated, but it likely plays an important role. Your risk of a heart attack or stroke is much higher if you are overweight, sedentary, smoke, have inadequately controlled high blood pressure, or if you have elevated LDL cholesterol. See a common denominator? We do. These are all things that, working with your diabetes team, you can control! In Chapter 4, we look at the ways healthy eating can help you control your blood pressure and your cholesterol.
Low blood glucose (hypoglycemia) is defined as a blood glucose level below 4.0mmol/L. As we mention earlier in this chapter, diabetes, per se, does not cause low blood glucose; rather, it is certain drugs – such as insulin or glyburide – used to treat diabetes that can lead to this condition.
Looking at the symptoms of low blood glucose
These are the common symptoms of low blood glucose:
✔ Anxiety
✔ Hunger
✔ Sweating
✔ Palpitations (noticing a rapid or excessively forceful heartbeat)
✔ Trembling of the hands
If