Blood glucose

The level of glucose (sugar) in your blood is controlled by insulin, and when your body can't use or make enough insulin this can result in low blood glucose (hypoglycaemia) or high blood glucose (hyperglycaemia).

Chronic hypoglycaemia can lead to brain and nerve damage. Chronic hyperglycaemia indicates diabetes - which if left untreated can cause progressive damage to body organs such as the kidneys, eyes, heart, blood vessels, and nerves and can increase your risk of heart attack or stroke.

A blood glucose test after fasting can determine if your blood glucose level is within a healthy range.

If your fasting blood glucose is greater than 7mmol/L on two tests you have diabetes.

If it's between 6.1 and 6.9mmol/L you may have a condition called pre-diabetes or impaired-fasting glycaemia. Pre-diabetes is a stage when blood glucose levels are higher than normal but not high enough for a diagnosis of type 2 diabetes.

If you have pre-diabetes you can and should do something about it. Studies have shown that changes to your lifestyle - moderate weight loss and regular exercise - can prevent or delay the onset of type 2 diabetes.

Risk factors

You are at risk for diabetes if you are overweight and aged 40 or older, or 30 years or older if you're of Maori, Pacific, Middle Eastern or Asian descent. Other risk factors include high blood pressure, low HDL cholesterol and high triglycerides, a family history of diabetes or giving birth to a baby weighing more than 4 kg.

The numbers:

• Aim for: 3.0 to 5.4 mmol/L. Important: these numbers are intended for screening healthy individuals. They are not appropriate target levels for people with diabetes.
  
  
• Check it: Every 3 years from age 55. Start younger and check more frequently if you have a high risk of type 2 diabetes.
  
  

Jargon buster

mmol/L: millimoles per litre - a measure of concentration using molecular count.