Monitoring your blood sugar (or blood glucose) is a key part of managing your health when you’re living with diabetes. Many people without diabetes are also interested in knowing more about their blood sugar levels.
When you eat food, your body breaks down the carbohydrates and converts them into simple sugars called monosaccharides. The most common one is glucose, which gets absorbed into your blood stream from the gut. Glucose is your body’s main source of fuel and is used to provide energy. When your blood sugar level rises after eating, a hormone made by the pancreas called insulin gets secreted into your blood. Insulin helps to move glucose out of your blood and into your body cells where it powers all of your body functions, like moving, breathing and thinking.
When the body becomes resistant to insulin, which can happen if the body stores too much fat inside cells in your muscles and liver, or if the pancreas does not produce enough insulin, then glucose can’t enter cells efficiently and levels rise in the blood. While a rise in blood glucose after eating is completely normal and what is meant to happen, levels can increase outside of the normal range if you have insulin resistance and/or your pancreas does not produce enough.
The key differences in blood sugar levels between those who do and do not have diabetes are listed in the Table.
A blood test to check blood glucose level can be done to check whether you have pre-diabetes or diabetes. People with diabetes are encouraged to monitor blood glucose levels regularly to learn about factors that cause blood sugar levels to rise above the normal range (hyperglycaemia) and factors that help keep them in range. Testing levels can also detect low blood sugar (hypoglycaemia), sometimes called a ‘hypo’.
When blood sugar levels are high over an extended period of time, some of the glucose sticks to haemoglobin (the part of a red blood cell that carries oxygen in your blood). This is called glycated (or glycosylated) haemoglobin or HbA1C for short. HbA1C levels are an indicator of how high your usual blood sugars have been over the previous 2-3 months.
Table of blood glucose and HbA1C levels
Glucose test | Definition | Normal glucose levels | Impaired glucose levels | Elevated glucose levels |
Fasting blood glucose | Measures the amount of glucose in the blood at the time of the blood test | 3.0 - 6.0 mmol/L | 6.1 - 6.9 mmol/L | Higher than or equal to 7.0 mmol/L |
Random blood glucose (non-fasting) | Measures the amount of glucose in the blood at a random time during the day (no matter how long it’s been since you’ve eaten) | 3.0 - 7.7 mmol/L | 7.8 - 11.0 mmol/L | Higher than or equal to 11.1 mmol/L |
Glucose tolerance test | Measures how well your body uses glucose (after drinking a sugary solution). | 3.0 - 7.7 mmol/L | 7.8 - 11.0 mmol/L | Higher than or equal to 11.1 mmol/L |
HbA1c | Reflects average blood glucose levels over past 2–3 months. Can be used to diagnose and monitor type 2 diabetes | Less than 6.0 % (42 mmol/mol) | 6.0 to 6.4 % (42 - 46 mmol/mol) | Higher than or equal to 6.5% (48mmol/L) |
If your results fall outside the normal range, your doctor may recommend further testing, lifestyle changes such as modifying your diet, managing your weight, increasing physical activity, along with medications when indicated. Early detection, timely action and regular follow-up are key to preventing diabetes complications.
If you are living with diabetes:
A HbA1c less than 7% (or 53 mmol/mol) | Indicates that it is likely that your diabetes is under good control. |
A HbA1c above 7% (or 53 mmol/mol) | Indicates that you are at increased risk of developing long term complications such as eye disease, kidney disease or nerve damage and possibly heart attack and stroke. |
Always discuss your results with your healthcare provider and/or diabetes team to understand what they mean for your individual health.
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