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Diabetes Mellitus: Clinical Presentations And Laboratory Diagnosis In Accordance To World Health Organization

Updated on February 17, 2014

A Diabetic Injecting Insulin


Clinical Manifestations

The clinical manifestations of diabetes are protean. Though, the symptoms are similar in both types of diabetes, in IDDM, they develop acutely whereas in the majority of NIDDM, the onset is insidious and often the condition may be asymptomatic. Around 50% cases present the classical symptoms of polyuria, polydipsia and weight loss (autophagia). These symptoms can be directly correlated with hyperglycermia and glycosuria. Other clinical presentations which warrant full investigation to exclude diabetes are:

  1. Non healing ulcers
  2. Recurrent respiratory or urinary tract infections
  3. Rapid changes in refraction of the eyes
  4. Steady and unexplained rapid weight loss
  5. Increased tendency for fungal infections like moniliasis, balanoposthitis and vulvitis
  6. Unexplained peripheral neuropathy
  7. Premature onset of ischemic heart disease, strokes or vascular occlusions;
  8. History of overweight babies and recurrent fetal loss
  9. Retinopathy
  10. Impotence in males; and
  11. Any vague ill health.

Well defined IDDM and NIDDM are distinguishable clinically and by investigation. In addition, there is a group with heterogenous features which in places like India for instance presents between the ages of 15 to 30 years. In this group, can be included: (1) pancreatic diabetes seen in South India and (2) young ketosis-resistant diabetics who are seen in North India without pancreatic calculi. Other clinical types are:

  1. Gestational diabetes: This is diabetes occurring only during pregnancy and remitting thereafter.
  2. Latent diabetes: This term is used to denote subjects who are known to have had diabetes previously. But who are normal at the time of assessment.
  3. Potential diabetes: These are such individuals who are at special risk of developing diabetes such as those with strong family history, large babies, and bad obstetric history.
  4. Brittle diabetes (Hyperlabile insulin dependent diabetes): This is seen usually in young subjects with IDDM (more women) in whome episodes of severe hyperglycemia and hypoglycemia occur. There have low insulin reserves.

World Health organization (WHO)

WHO_HQ_main_building,_Geneva,_from_North | Source


A well-developed case with classical symptoms can be diagnosied clinically, but since many cases may be asymptomatic, diabetes should be suspected even in the absence of symptoms. Asymptomatic cases will be diagnosed only if the index of suspicion is high. Always, the diagnosis should be confirmed by laboratory investigations. Fasting blood glucose levels above 8 mmol/liter (140 mg/dl) or postprandal blood glucose levels above 11 mmol/liter (200 mg/dl) are diagnostic.

WHO Criteria For Diagnosis Of Diabetes And Impaired Glucose Tolerance

Venous Whole Blood
Capillary whole blood
Venous Plasma
Greater than 180 mg/dl
Greater than 120 mg/dl
Greater than 140 mg/dl
2 hours after glucose load
Greater than 120 mg/dl
Greater than 200 mg/dl
Greater than 200 mg/dl
Less than 120 mg/dl
Less than 120 mg/dl
Less than 140 mg//dl
2 hours after glucose load
120- 180 mg/dl
Less than 200 mg/dl
Less than 200 mg/dl

Laboratory Investigations

Urine Tests: These tests can be used for initial screening and for follow- up of cases under treatment. Since the urinary glucose does not always directly reflect the blood glucose level, urine examination should not be fully relied upon for diagnosis and monitoring therapy. The renal threshold for glucose (normal 10 mmol/liter to 180 mg//dl) rises with age. Still, the value of urine examination cannot be over emphasized since proteinuria and ketonuria can be detected only by this test.

Glucose is tested by the Benedict’s test and clinitest (Chemtab) which detect reducing substances nonspecifically. While glucose is by far the commonest reducing substance in urine, the possibility of other reducing substances should be kept in mind and the enzyme methods (employing glucose oxidase) which are specific for glucose should be employed.

If the Benedict’s test is positive and the glucose oxidase test is negative, the presence of other reducing substances such as ascorbic acid, aspirin, or lactose should be suspected.

Blood sugar estimation: Various methods are employed to estimate blood glucose. The methods using copper-reduction (Folin-Wu of Nelson-Somogyi) also detect other reducing substances like uric acid and creatinine and hence their values are 20- 30 mg/dl higher than those obtained by glucose oxidase methods which give the true values. Blood sugar estimations are mandatory for confirming the diagnosis of diabetes. Both fasting and postprandial values should be estimated. In mild diabetes, the fasting blood sugar values may be below 140 mg/dl and therefore the diagnosis is likely to be missed if only fasting blood sugar is estimated.

© 2014 Funom Theophilus Makama


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