How is the diagnosis of diabetes made ?

Why is diabetes important ?

1 – About 5% of the population are affected by it.

2 – It is the third leading cause of death in the USA

Although there are some clinical features for diabetes, its final diagnosis is made by

laboratory methods.

There are two major subtypes of diabetes that the main pathway of their diagnosis is the same.

ADA (American Diabetes Association) recommends that :

Fasting plasma glucose or oral glucose tolerance test should be considered in all asymptomatic people at age 45.

Follow up testing is needed every 3 years.

Hyperglycemia should be differentiated from diabetes. In other word each hyperglycemia is not diabetes !.

There are 3 main tests for plasma glucose measurement.

Fasting plasma glucose :

Plasma specimen collected after a 12 to 14 hour fast vary less among individuals than do specimens collected at other times.

Oral glucose tolerance test is more sensitive than fasting plasma glucose early in the course of type 2 diabetes.

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Plasma glucose is measured fasting,then every 30 minutes for 2 hours after an oral glucose load which is 75 g for nonpregnant adults and 1.75 g/kg for children up to 75 g. Glucose is dissolved in 300 ml of water and ingested over 5 minutes.

OGTT should not be performed on:

Hospitalized patients Acutely ill patients Inactive patients

Abnormal result of any FBS, Plasma Glucose or 2h pp glucose with classic symptoms of diabetes = Diabetes

2h pp : 2-hour postload plasma glucose

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normal diabetes

Fasting PlasmaGlucose

PlasmaGlucose

2h pp

Impaired tests but not exactly diabetes

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Normal Impaired Diabetes

FBS

GTT 2nd hour

Factors other than diabetes which may influence the oral glucose tolerance test

20% of OGTTs fall into the nondiagnostic category. The OGTT should be performed on two separate occasions before the

results are considered abnormal

Prediabetes:

Before people develop type 2 diabetes, they almost always have "prediabetes"—blood glucose levels that are higher than normal but not yet high enough to be diagnosed as diabetes. There are 57 million people in the United States who have prediabetes. Recent research has shown that some long-term damage to the body, especially the heart and circulatory system, may already be occurring during prediabetes.

http://www.diabetes.org/diabetes-basics/prevention/pre-diabetes/

What goals and treatment modalities should be the focus of prediabetes management?

As prediabetes progresses, drug therapies directed towards hyperglycemia and the individual coronary heart disease risk factors may be required. …. http://www.aace.com/meetings/consensus/hyperglycemia/hyperglycemia.pdf

References:

Burtis-C, Ashwood-E, Bruns-D,Tietz Fundamental of Clinical Chemistry, 6th Edition, Saunders, 2008

Henry- JB – Clinical Diagnosis & Management By Laboratory Methods, 19th Edition, Saunders, 1996

McPhee-S J, Papadakis- M, Current Medical Diagnosis And treatment, 49th Edition, Lange, 2010

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http://www.diabetes.org/diabetes-basics/prevention/pre-diabetes http://www.aace.com/meetings/consensus/hyperglycemia/hyperglycemia.pdf