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What is the optimal blood glucose (sugar) range?

Blood-glucose levels are measured in units called mmol/L (pronounced milli-moles-per-litre) everywhere in the world, apart from the USA. That’s why you’ll occasionally see strange blood glucose readings like 140 or 220 in books or on the internet. To convert the USA scores (mg/dl) back to mmol/L simply divide the USA figure by 18.

Check with your doctor about the individual blood glucose you should aim for. In general, optimal blood glucose goals are:

Before meals: 4-7 mmol/L

At bedtime: 6-10 mmol/L

Before exercise: 5-15 mmol/L

You may need to consult your doctor and change your treatment plan if:

  • Blood–glucose is consistently lower than 4 mmol/L or higher than 10 mmol/L before meals.
  • Blood glucose is consistently lower than 6 mmol/L or higher than 12 mmol/L at bedtime.
  • Blood glucose goals may be modified for children and others who are at greater risk of hypoglycaemia.

To maintain ‘normal’ blood-glucose levels, you now need to do the job of your pancreas. This means injecting insulin several times a day, regularly monitoring blood-glucose levels and making constant decisions about how much insulin to inject to keep your blood glucose as close to the normal range as possible. One of the reasons to do this is to help you feel your best and give you more energy. Aiming for ‘normal’ blood-glucose levels will also help prevent or delay the development of the long-term health complications of diabetes.

The Good News...

Research shows that people who check their blood-glucose levels regularly and adjust their insulin, diet, and exercise to achieve better blood glucose level readings, reduce their risk of developing damage to those organs vulnerable to complications.

Constant high blood glucose is toxic to the body. Cells in your brain, nerves, eyes, kidneys and blood vessels readily absorb glucose without insulin being present — these organs in particular are vulnerable to complications.

How to know if your diabetes is under control

Checking the level of glucose in your blood and keeping a record of the levels is an important part of taking care of your diabetes. This allows you to identify the patterns of high or low blood-glucose levels. The information will also help you and your doctor or diabetes team to balance food, exercise and insulin doses.

Ideally you should aim to do at least four blood glucose checks a day. To get the most out of monitoring, your diabetes team may advise you to check your blood-glucose levels before and then two to three hours after food. It is also a good idea to monitor before, during and after exercise.

If your blood glucose level is high, such as at the time of diagnosis, or when you are unwell, you should also monitor for ketones. You can do this by checking your blood using a blood glucose meter that also measures for ketones or by checking your urine. Ketones in the blood or urine can also indicate that your insulin levels are too low and that additional insulin needs to be taken as a matter of urgency so that your body can use glucose for energy rather than fat.

There is no avoiding the fact that pricking your finger can be painful. There are various finger pricking devices on the market and you may find one more comfortable than another. Most devices allow you to adjust the depth of the needle if you are not getting a large enough drop of blood. The tips of your fingers are also more sensitive so try pricking your finger off to one side. Also be careful how vigorously you pump your finger for blood once your finger is pricked. This can squeeze blood into the surrounding tissue, causing bruising and discomfort. It might be encouraging to know that monitoring your blood glucose becomes less painful over time!

Tips to Improve Your Blood Glucose Control

  • Keep a good record of your blood-glucose levels
  • Review your blood glucose records regularly to look for patterns of highs/lows
  • Work with your doctor or DSN to make adjustments to your insulin intake, diet and exercise until your control improves
  • Learn what causes highs and lows for you. The more you recognise what triggers highs/lows, the better you will be able to adjust your insulin, carbohydrate intake or exercise to avoid problems
  • Don’t expect perfection! Just aim to get more of your readings within target
  • Ask for help from your doctor or diabetes healthcare team when you need it.
JDRF has a global research portfolio aiming to cure type 1 diabetes one day. In the meantime, JDRF is also funding research to improve treatments for people with type 1 today. Please help us continue this vital work by donating to type 1 research now