Diagnosis & Classifications
Who should test?

By this we mean whom should go for testing for Diabetes despite the absence of the classical symptoms and not yet known to be a Diabetic .
Inhere we recommend testing for diabetes for all persons aged 40 or older and, if normal, should be repeated at 3-year intervals, however this testing is preferred in all cases to be done annually and at the same time should be done at a younger age and more frequently, in persons with risks listed below :
  • Obese persons (body mass index BMI more than 27 in males and 25 in females )
  • Those having a first-degree relative with Diabetes
  • Certain ethnic population like African Americans or Asians
  • Females with a history of delivering large babies weighing more than 9 pounds or those who were diagnosed with gestational diabetes .
  • All hypertensive persons (blood pressure greater than or equal to 140/90)
  • Persons with abnormal lipid profiles , high density lipoprotein cholesterol level less than or equal to 35 mg/dl (men) or less than or equal to 45 mg/dl (women), and/or a total cholesterol level above 200 mg/dl and/or a triglyceride level equal to or greater than 250 mg/dl
  • persons with impaired glucose tolerance ( 140 – 199 mg/dl ) or impaired fasting glucose ( 110 – 125 mg/dl ) on previous testing
Diagnostic Figures for Diabetes
  1. Random plasma glucose equal or more than 200 mg/dL on two separate occasions in presence or absence of the symptoms related to hyperglycemia : frequent urination (polyuria), excessive drinking of water and fluids (polydipsia) and unexplained weight loss .
  2. Fasting plasma Glucose (FPG) equal or more than 126 mg/dL on two separate occasions
  3. Two hours plasma glucose equal or more than 200 mg/dL during oral glucose tolerance test (OGTT) on two separate occasions.
Important: The Glycated Haemoglobin HbA1c is not recommended for diagnosis of Diabetes.

Criteria for the Diagnosis of Diabetes
Diagnosis of Diabetes
(mmol/L / mg/dl)
Stage Fasting Plasma Glucose Test (FPG) Random Plasma Glucose Test Oral Glucose Tolerance Test (OGTT)
Diabetes greater than or equal to 7.0 / 126 greater than or equal to 11.1 / 200 plus symptoms *** greater than or equal to 11.1 / 200 ****
Impaired Glucose Homeostasis Impaired Fasting Glucose (IFG) greater than or equal to 6.1 / 110 and less than 7.0 / 126 Impaired Glucose Tolerance (IGT) greater than or equal to 7.8 / 140 and less than 11.1 / 200
Normal less than 6.1 / 110 less than 7.8 / 140
  1. The fasting plasma glucose is the preferred test for diagnosis, but any one of the three listed is acceptable. Fasting is defined as no caloric intake for at least 8 hours (better to be overnight fast).
  2. Random is defined as any time of day without regard to time since last meal. Symptoms are the classic ones related to the hyperglycemia such as polyuria, polydipsia, and unexplained weight loss.
  3. Oral glucose tolerance test should be performed using a glucose load containing the equivalent of 75 g anhydrous glucose dissolved in water. The oral glucose tolerance test is not recommended for routine clinical use.
Classification of Diabetes

The first classification of diabetes dates back to about 56 years ago in 1947 where diabetes was classified into two main types: the Juvenile onset diabetes and maturity onset diabetes, In 1979 both WHO and the national diabetes data group established a new classification: Insulin Dependent Diabetes Mellitus IDDM & Non Insulin Dependent Diabetes Mellitus NIDDM and this classification was published by WHO in 1980 and modified in 1985. In both the 1980 and 1985 reports other classes of diabetes included also other types like Impaired Glucose Tolerance (IGT) and Gestational Diabetes Mellitus (GDM). In 1995 an international Expert Committee, working under the sponsorship of the American Diabetes Association, was established to review the scientific outcome since the last classification 1979 to decide if there should be some changes to the classification and diagnosis of diabetes or not .

This report of this committee indicated a strong need to do significant changes either in the criteria for diagnosis or for the classification of diabetes, this classification was based on the etiology of the disease. This means that the old classification of diabetes in 1947 was based on the on age of the patients wether they are juvenile or mature, the 1979 classification was based upon the type of treatment received wether it is Insulin or not While the last classification in 1998 was based upon the aetiology of diabetes which seems to be the most logic and accepted classification till now.

Aetiological classification of Diabetes ( adapted Diabetes Care , 2003 )
I. Type 1 diabetes (ß-cell destruction, usually leading to absolute insulin deficiency)
A. Immune mediated B. Idiopathic
II. Type 2 diabetes (may range from predominantly insulin resistance with relative insulin deficiency to a predominantly secretory defect with insulin resistance)
III. Other specific types
A. Genetic defects of ß-cell function
1. Chromosome 12, HNF-1 (MODY3) 2. Chromosome 7, glucokinase (MODY2)
3. Chromosome 20, HNF-4 (MODY1) 4. Mitochondrial DNA
5. Others
B. Genetic defects in insulin action
1. Type A insulin resistance 2. Leprechaunism
3. Rabson-Mendenhall syndrome 4. Lipoatrophic diabetes
5. Others
C. Diseases of the exocrine pancreas
1. Pancreatitis 2. Trauma/pancreatectomy
3. Neoplasia 4. Cystic fibrosis
5. Hemochromatosis 6. Fibrocalculous pancreatopathy
7. Others
D. Endocrinopathies
1. Acromegaly 2. Cushing’s syndrome
3. Glucagonoma 4. Pheochromocytoma
5. Hyperthyroidism 6. Somatostatinoma
7. Aldosteronoma 8. Others
E. Drug- or chemical-induced
1. Vacor 2. Pentamidine
3. Nicotinic acid 4. Glucocorticoids
5. Thyroid hormone 6. Diazoxide
7. ß-adrenergic agonists 8. Thiazides
9. Dilantin 10. -Interferon
11. Others
F. Infections
1. Congenital rubella 2. Cytomegalovirus
3. Others
G. Uncommon forms of immune-mediated diabetes
1. "Stiff-man" syndrome 2. Anti-insulin receptor antibodies
3. Others
H. Other genetic syndromes sometimes associated with diabetes
1. Down’s syndrome 2. Klinefelter’s syndrome
3. Turner’s syndrome 4. Wolfram’s syndrome
5. Friedreich’s ataxia 6. Huntington’s chorea
7. Laurence-Moon-Biedl syndrome 8. Myotonic dystrophy
9. Porphyria 10. Prader-Willi syndrome
11. Others
IV. Gestational diabetes mellitus (GDM)