How Do You Know You Have Pre-diabetes?

Pre-diabetes

Pre-diabetes or impaired glucose tolerance is described by blood-glucose levels, which are raised above the upper normal value, but below the limit (threshold) for diabetes mellitus. It is important to diagnose pre-diabetes early, because it helps assess the risk of developing type 2 diabetes mellitus and stop the progression to diabetes and cardiovascular disease later in life.

Pre-diabetes: definition

Pre-diabetes is described differently by the World Health Organisation (WHO) and the American Diabetes Association (ADA).

ADA definition

If an individual has one of the following three features, he or she has pre-diabetes and are at risk of developing type 2 diabetes mellitus.

Impaired fasting blood sugar or impaired fasting glucose (IFG)

A blood sample from a vein (venous sample) should be obtained following an overnight fast for eight to fourteen hours. Fasting blood sugar of 100-125 mg/dl (5.6-6.9 mmol/l) is described as IFG. This limit was introduced in 2003. It was 110-125 mg/dl (6.1-6.9 mmol/l) before 2003. Therefore, the new threshold value increases the sensitivity and helps identify more people, who are at increased risk for diabetes.

Impaired glucose tolerance (IGT)

The oral glucose tolerance test (OGTT) should be carried out in the morning. Initially, fasting plasma glucose is tested following an eight to fourteen hours of fasting. Then, the patient should consume a calculated quantity of glucose in water. A second venous blood sample should be obtained two hours following the glucose drink.

For adults: 75 g glucose in 300 ml water
For children: 1.75 g glucose/kg body weight

If the plasma glucose level, which is obtained two hours following 75 g oral glucose challenge, is more than 140 mg/dl (7.8 mmol/l) but lower than 200 mg/dl (11 mmol/l), it indicates IGT.

Haemoglobin A1c (HbA1c)

Glycated haemoglobin (HbA1c) is a type of haemoglobin. HbA1c test does not need fasting and reflects the average blood-glucose level over past few months. Since 2010, an HbA1c level of 5.7-6.4 % is described as a pre-diabetes indicator. However, it is somewhat controversial. It has not been properly analysed in children.

WHO definition

If a person has one or both following features, he or she has pre-diabetes and are at raised risk of type 2 diabetes.

Impaired fasting blood sugar or impaired fasting plasma glucose (IFG)

Fasting plasma glucose of 110-125 mg/dl (6.1-6.9 mmol/l) shows IFG.

Impaired glucose tolerance (IGT)

The plasma glucose level, which is obtained two hours following 75 g oral glucose challenge, is more than 140 mg/dl (7.8 mmol/l) but lower than 200 mg/dl (11 mmol/l).