Blood Glucose Level
Glucose is one of the body's principle sources of energy. It's a type of sugar that is created from the food we eat. When you eat the digestive system breaks carbohydrates down into different types of sugars, the primary and most important one for us being glucose.
What is blood glucose?
After carbohydrates have been broken down by the digestive system, the glucose is delivered straight into the bloodstream. Blood glucose refers to the level of glucose being carried in the blood. The pancreas then releases insulin, which is what enables the glucose to leave the bloodstream and nourish the cells in our body.
Without insulin, glucose would remain in our bloodstream and the cells would be starved of energy. Once cells are full, excess glucose is converted to glycogen that is stored in the liver and the muscles.
Normal blood sugar levels
Blood sugar levels are most commonly expressed in terms of the number of milimoles of glucose per litre of blood (mmol/l). The other way to measure levels is to look at the weight of glucose within the blood, which is expressed as the milligrams of glucose per decilitre of blood (mg/dl). The normal blood sugar level for humans is 5mmol/l or 90mg/dl.
It's normal for blood sugars to fluctuate within certain healthy limits. Blood sugar levels in the range of 3.6mmol and 5.8mmol are considered normal. After you eat, your blood sugar levels will naturally increase to the higher end of this range, which will prompt the pancreas to release insulin to break it down. As the glucose is then absorbed into cells, or converted for storage, your blood sugar levels will fall back to normal. Usually within an hour of eating.
If you're blood sugar levels fall to the lower end of this range, the pancreas will respond by releasing a hormone called glucagon. This hormone triggers a reaction to breakdown the glycogen and stores it as glucose, which will bring the blood sugar levels back to normal. Normally our blood sugar is at its lowest first thing in the morning, after fasting overnight.
Measuring blood glucose levels
To measure your blood glucose levels, a doctor will take a blood sample from you and perform some of the following tests:
- HbA1c or glycohemoglobin test – This test provides a longer term historical view of your sugar levels over the previous three months. It looks at the amount of glucose bound to the haemoglobin in your red blood cells.
- An FPG (Fasting Plasma Glucose) test – This tests your blood sugar levels after fasting for eight hours.
- An Oral Glucose Tolerance Test (OGTT) – After eight hours of fasting, you're given a sugary drink. Your blood glucose levels are tested after two hours to see how much sugar remains in your blood. Tests are often performed in the morning making it easier to fast for a long period of time.
If your blood glucose levels are consistently high, you may be diagnosed as having pre-diabetes depending on how high your glucose levels are.
|Diagnosis||A1c Percent||FPG mg/dL||OGTT mg/dL|
|Diabetes||6.5 or above||126 or higher||200 or higher|
|Pre-diabetes||5.7 to 6.4||100 to 125||140 to 199|
|Normal||5||99 or below||140 to 199|
If you're diagnosed with diabetes you may be required to carry out tests at home to monitor your blood sugar levels. You can do this using a device such as a glucose meter. If your diabetes is advanced, you may need to check your glucose levels several times a day to ensure that you don't have hyperglycaemia (high blood sugar) or hypoglycaemia (low blood sugar).
Problems with high glucose levels
If high glucose levels, also known as hyperglycaemia, are left untreated they can lead to a lot of serious health conditions, including:
- Kidney failure, requiring dialysis
- Cardiovascular problems, heart attacks and strokes
- Vision impairment and blindness
- Damaged immune systems and increased susceptibility to infections
- Erectile dysfunction and circulation problems
- Neuropathy and loss of sensation in your feet, hands and legs
- Slow-healing wounds and in rare cases amputation
Lowering high blood glucose
Your plan for lowering your high blood glucose levels will depend on how high they are and whether you're diagnosed as a pre-diabetic, a type 1 diabetic or a type 2 diabetic. These can include:
- Introducing a healthy low GI-Diet and avoiding junk and processed food. Losing weight and controlling your portion size can also have a huge impact on lowering your glucose levels. Getting moderate and regular exercise that can help your body better use insulin and can lower your blood sugar levels and your blood pressure. It's recommend that you try and get at least 30 minutes of exercise, five days a week.
- Using a medication like Metformin (Glucophage), which can help decrease the glucose levels in the blood and also helps the body cope better with low production of insulin. It's commonly prescribed for people with type 2 diabetes and pre-diabetes.
- Using insulin injections or pumps. This is commonly required when you've type 1 diabetes, as you will be unable to produce enough insulin yourself to sufficiently lower your blood glucose levels.