Fact Files : Diabeties & Blood Glucose Monitoring

Keeping track of your blood glucose level is an important part of managing diabetes. It keeps you informed of how well your diabetes is being controlled — good glycaemic control (control of your blood glucose) will ultimately help you to avoid or delay diabetic complications.

Blood glucose control

Achieving well-controlled diabetes means keeping the amount of sugar in your blood — your blood glucose level — as closely as possible within the normal range.

Targets for glycaemic control

How often do I check my blood glucose?

As shown above it is usually recommended that your blood glucose levels are taken before a meal or 1 ½ - 2 hours after a meal, or at both times. However, you may be advised to monitor at different times depending on your needs i.e. health status, lifestyle, pregnancy, medications etc. Some people may need to monitor up to several times daily, while others less frequently.

One suggestion to evaluate your control is through staggered monitoring of blood glucose (SMBG) in which you test 2-3 times per day at different meal times as shown below:

Table 1 presents one of many options for SMBG:

What are the advantages of checking my blood glucose?

Recording your blood glucose levels in a log book will provide you, your doctor and dietitian with a useful source of information when making decisions about managing your diabetes.

Being unaware of persistently high blood glucose levels can put you at risk of immediate complications of diabetes such as diabetic ketoacidosis. Equally important is identifying and quickly treating dangerously low blood glucose levels, which can lead to a hypoglycaemic coma.

What causes glucose levels to go up and down?

There are a number of common causes for glucose levels to increase or decrease. These include:

• Food
  o Time foods are eaten
  o Type of food – carbohydrates foods (i.e. bread and bread products, cereals, pasta, rice, fruit, starchy vegetables, milk, yoghurt, lollies, soft drink etc) have an immediate effect on blood sugar levels but the response depends on the type of carbohydrate foods eaten. Carbohydrate foods that break down quickly during digestion and produce a fast and high glucose response have a high glycemic index (GI) whereas those that digest more slowly and have a slow and gradual affect on blood glucose have a low GI.
  o Amount of food - the total volume of food eaten at meals times (esp. carbohydrate foods) have varying effects on blood sugar levels.
• Exercise or physical activity
• Illness and pain
• Diabetes medication
• Alcohol
• Emotional stress
• Other medications
• Testing techniques

Knowing how your blood glucose changes in response to these influences helps you to plan your day and modify your treatment to optimise your diabetes control. Monitoring also tells you how well your diabetes treatment — whether medication or lifestyle changes — is working.

Are HIGH blood glucose levels dangerous?

Sometimes you may get a higher BGL reading than usual and you may not be able to figure out the reason. You may need to contact your doctor or dietitian for assistance. However, it is only when BGLs are consistently higher (i.e. consistently above 8mmol/l 2hrs after meals) than they ought to be over weeks or months that the damage-causing complications can occur. This includes increased risk of heart attack, stroke, peripheral vascular disease, poor eyesight, renal disease, and neuropathy.

This gives more reason for you to do your best to aim for optimal blood glucose control and stay well with diabetes.

What are other measures to determine my glycemic control?

Apart from regularly checking your own blood glucose level, your doctor may recommend that you have your glycosylated haemoglobin (HbA1c) level measured every 3 to 6 months. This measurement is obtained from a simple blood test and is generally considered as the gold standard for the assessment of the overall glycemic control

Haemoglobin is a protein contained within red blood cells. Sugar in the blood sticks to haemoglobin causing it to become ‘glycosylated’. If your sugar levels have been consistently high, then the haemoglobin will have a higher percentage of sugar attached to it.

ideal HbA1c	high HbA1c

Your HbA1c level should ideally be 7% or less to decrease your risk of developing complications.

Table 2 represents the approximate mapping between HbA1c values and average blood glucose measurements over the previous 4-12 weeks.

References:
Parkin CG, Brooks N (2002). Is postprandial glucose control important? Is it practical in primary care settings?
-Clinical Diabetes Vol 20, No. 2
Department of Health – What is glycosylated hemoglobin (HbA1c) fact sheet
- Diabetes Centre, Royal Adelaide Hospital, 2003 Diabetes In SA

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