Diagnosis .. continued...
The A1C test measures your average blood glucose for the past 2 to 3 months. The advantages of being diagnosed this way are that you don't have to fast or drink anything.
Diabetes is diagnosed at an A1C of greater than or equal to 6.5%
Normal - less than 5.7%
Prediabetes -5.7% to 6.4%
Diabetes - 6.5% or higher
Fasting Plasma Glucose (FPG)
This test checks your fasting blood glucose levels. Fasting means after not having anything to eat or drink (except water) for at least 8 hours before the test. This test is usually done first thing in the morning, before breakfast.
• Diabetes is diagnosed at fasting blood glucose of greater than or equal to 126 mg/dl
Fasting Plasma Glucose (FPG)
Normal - less than 100 mg/dl
Prediabetes - 100 mg/dl to 125 mg/dl
Diabetes - 126 mg/dl or higher
Oral Glucose Tolerance Test (also called the OGTT)
The OGTT is a two-hour test that checks your blood glucose levels before and 2 hours after you drink a special sweet drink. It tells the doctor how your body processes glucose.
Diabetes is diagnosed at 2 hour blood glucose of greater than or equal to 200 mg/dl
Oral Glucose Tolerance Test (OGTT) :
Normal : less than 140 mg/dl
Prediabetes : 140 mg/dl to 199 mg/dl
Diabetes : 200 mg/dl or higher
Random (also called Casual) Plasma Glucose Test
This test is a blood check at any time of the day when you have severe diabetes symptoms.
• Diabetes is diagnosed at blood glucose of greater than or equal to 200 mg/dl
Why are good blood sugar levels important?
It is important that you control your blood glucose levels as well as you can as too high sugar levels for long periods of time increases the risk of diabetes complications developing.
Diabetes complications are health problems which include:
• Kidney disease
• Nerve damage
• Retinal disease
• Heart disease
This list of problems may look scary but the main point to note is that the risk of these problems can be minimised through good blood glucose level control. Small improvements can make a big difference if you stay dedicated and maintain those improvements over most days.
Guide to HbA1c
HbA1c forms when haemoglobin joins with glucose in the blood
HbA1c is a term commonly used in relation to diabetes. This guide explains what HbA1c is, how it differs from blood glucose levels and how it's used for diagnosing diabetes.
What is HbA1c?
The term HbA1c refers to glycated haemoglobin. It develops when haemoglobin, a protein within red blood cells that carries oxygen throughout your body, joins with glucose in the blood, becoming 'glycated'.
By measuring glycated haemoglobin (HbA1c), clinicians are able to get an overall picture of what our average blood sugar levels have been over a period of weeks/months.
For people with diabetes this is important as the higher the HbA1c, the greater the risk of developing diabetes-related complications.
HbA1c is also referred to as haemoglobin A1c or simply A1c.
Definition of HbA1c
HbA1c refers to glycated haemoglobin (A1c), which identifies average plasma glucose concentration.
How does HbA1c return an accurate average measurement of average blood glucose?
When the body processes sugar, glucose in the bloodstream naturally attaches to haemoglobin.
The amount of glucose that combines with this protein is directly proportional to the total amount of sugar that is in your system at that time.
Because red blood cells in the human body survive for 8-12 weeks before renewal, measuring glycated haemoglobin (or HbA1c) can be used to reflect average blood glucose levels over that duration, providing a useful longer-term gauge of blood glucose control.
If your blood sugar levels have been high in recent weeks, your HbA1c will also be greater.
What are the benefits of lowering HbA1c?
Two large-scale studies and the Diabetes Control and Complications Trial (DCCT) - demonstrated that improving HbA1c by 1% for people with type 1 diabetes or type 2 diabetes cuts the risk of microvascular complications by 25%.
Microvascular complications include:
• Diabetic nephropathy (kidney disease)
Research has also shown that people with type 2 diabetes who reduce their HbA1c level by 1% are:
• 19% less likely to suffer cataracts
• 14% less likely to suffer heart failure
• 43% less likely to suffer amputation or death due to peripheral vascular disease
How does HbA1c differ from a blood glucose level?
HbA1c provides a longer-term trend, similar to an average, of how high your blood sugar levels have been over a period of time.
An HbA1c reading can be taken from blood from a finger but is often taken from a blood sample that is taken from your arm.
Blood glucose level is the concentration of glucose in your blood at a single point in time, i.e. the very moment of the test.
This is measured using a fasting plasma glucose test, which can be carried out using blood taken from a finger or can be taken from a blood sample from the arm.
However, fasting glucose tests provide an indication of your current glucose levels only, whereas the HbA1c test serves as an overall marker of what your average levels are over a period of 2-3 months.
Note that the HbA1c value, which is measured in mmol/mol, should not be confused with a blood glucose level which is measured in mg/dl. Use our HbA1c conversion tool to help with switching between the two measurement units.
Results indicating prediabetes are:
• An A1C of 5.7% – 6.4%
• Fasting blood glucose of 100 – 125 mg/dl
• An OGTT 2 hour blood glucose of 140 mg/dl – 199 mg/dl