Family doctor

Overview

Frequent blood glucose testing by people with diabetes is important to help get good control and prevent long-term complications. It is now known that good control of blood glucose levels can prevent or reduce complications. A combination of self testing and HbA1c testing is important to gain a broad picture of diabetic control .

Why is testing important for diabetics?

Carefully monitoring of blood sugar levels (blood glucose) gives valuable information to help obtain good control which can delay the onset or progression of long term diabetic complications.

People with type 1 and type 2 diabetes usually monitor their blood sugar themselves using thumb prick blood tests. Although most people understand their particular control methods prevent day to day effects, they may not appreciate how important self-monitoring is for long term health.

Frequent careful monitoring can show what may be happening long term, and can show how positive changes to diet, exercise or weight changes are improving a patient's diabetes. Close monitoring of blood glucose levels - too high or low - allows control of day to day effects, however this can also indicate a changes over time and allow intervention to prevent diabetic complications.

What are the long term complications?

The major long-term consequences of diabetes relate to the damage of the blood vessels and nerves. Long term complications of high blood glucose levels include loss of kidney function; nerve damage and loss of sensation and circulation to extremities; eye damage; and a higher incidence of heart disease and stroke. These complications develop gradually over time directly as a result of high blood glucose levels, so unless levels are well monitored and controlled, the patient is risking development of some or all of these complications.

Good long term control reduces complications;

Results of a long term study, the United Kingdom Prospective Diabetes Study, showed tight control of blood glucose levels markedly reduced complications. In the study, 3867 Type 2 diabetes patients were monitored over 10 years. Tight control resulted in 25% reduction in eye, kidney and nerve complications, and 10% reduction in diabetes-related deaths.

The study also indicated good control of high blood pressure can help to reduce diabetic complications.

What are the vital tests?

As well as regular self testing and recording of blood glucose levels by thumb prick blood tests, a few times a year a laboratory test of HbA1c (glycosylated haemoglobin) levels should be taken.

Other tests that are usually performed over time include: urine test to monitor kidney function; blood fat levels (cholesterol & triglyceride levels); and tests for kidney function.

Regular blood pressure assessment and treatment when appropriate, is needed. Examination of the feet by health professionals is necessary as the patient may not be aware of loss of sensation from early nerve damage. An eye specialist should review eyes every 1 to 2 years, depending on test results.

What is HbA1c?

HbA1c (glycosylated haemoglobin) is collected in red blood cells when they are produced. It gives an indication of blood sugar levels over a couple of months - the average lifespan of a red blood cell. As such it shows average blood glucose levels over time, compared to the thumb prick test, which indicates blood glucose at the moment of testing.

The combination of results from HbA1c tests and thumb prick tests give a better indication of variations in blood glucose levels than either test alone.

Why do self test meter readings sometimes vary?

Sometimes meter readings from self testing can vary, even within minutes.

This may be due to the condition of test strips - these are affected by light and temperature variations, so keep them sealed in a cool dark place. Results may also vary between manufacturers' products, so use one product. Test strips have expiry dates - check these.

Different meters may work differently. It is best to use one meter consistently to establish a pattern of results to rely on.

Sometimes the first test may include skin products, and the second, clotting compounds which both affect results. Pay careful attention to washing and drying hands before testing, and use a consistent test method.

It is also important to have meters checked and maintained regularly, especially if results are changing.

How often should testing occur?

Diabetics on insulin control should self test 3-4 times everyday, especially before bed. Type 2 diabetics on medication control should self test around 3 times a day, a few times a week.

If unwell, diabetics should test more frequently, likewise if there are changes to exercise regimes or diet.

Good times to test during the day are first thing in the morning, and before and after meals. Daily test times should be varied to get a good picture of changes to blood glucose levels right throughout the day.

What do test results mean?

Results of HbA1c tests show the average level of blood glucose over a couple of months. If the HbA1c level is above 7%, options for diabetes management should be reviewed.

Recent stress or lifestyle changes may be taken into account. Changes to physical activity, diet, and weight will all be discussed and recommendations given where appropriate. Injection technique or how regularly medication is taken will be examined.

If the HbA1c level is above 8%, referral to a diabetes specialist may occur, and medication may be altered or a more intensive insulin regime used.

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