I.1.3. Definition, classification
of diabetes mellitus and other categories of glucose regulation
Diabetes mellitus is a group of metabolic diseases of multiple
etiology characterized by hyperglycemia resulting from defects in insulin
secretion, insulin action, or both (Craig et al.,
2009).The chronic hyperglycemia of diabetes is associated with
long-term damage, dysfunction, and failure of various organs, especially the
eyes, kidneys, nerves, heart, and blood vessels (Craig et al.,
2009).
Assigning a type of diabetes to an individual often depends on
the circumstances present at the time of diagnosis, and many diabetic
individuals do not easily fit into a single class. Thus, for the clinician and
patient, it is less important to label the particular type of diabetes than it
is to understand the pathogenesis of the hyperglycemia and to treat it
effectively (ADA, 2009, Rasilainen et al., 2004).
Table I : Diabetes classification:
etiologic types and stages
|
Stages (WHO, 1999)
Types
|
Normoglycemia
|
Hyperglycemia
|
|
Normal glucose tolerance
|
Impaired Glucose regulation
IGT and/or IFG
|
Diabetes mellitus
|
|
Not insulin requiring
|
Insulin requiring for control
|
Insulin requiring for survival
|
|
Type 1
· Autoimmune
· Idiopathy
Type 2
· Predominantly insulin resistance
· Predominantly insulin secretary defects
Other specific types
|
|
|
|
|
|
|
Gestational diabetes
|
|
|
|
|
|
I.1.4. Signs and symptoms
The classical symptoms of diabetes are polyuria (frequent
urination), polydipsia (increased thirst) and polyphagia (increased hunger)
weight loss, and blurred vision. Impairment of growth and susceptibility to
certain infections may also accompany chronic hyperglycemia (Cooke
et al., 2008). Symptoms may develop rapidly (weeks or months)
in type 1 diabetes while in type 2 diabetes they usually develop much
more slowly and may be subtle or absent. Type 1 should always be suspected
in cases of rapid vision change, whereas with type 2 changes are generally
more gradual, but should still be suspected (Cooke et al.,
2008).
I.1.5. Diagnostic criteria for
diabetes mellitus
Three ways to diagnose diabetes are possible, and each, in the
absence of unequivocal hyperglycemia, must be confirmed, on a subsequent day,
by any one of the three methods.
Criteria for the diagnosis of diabetes mellitus
1. Symptoms of diabetes plus casual plasma glucose
concentration =11.1 mmol/l (200 mg/dl).Casual are defined as any time of day
without regard to time since last meal.
2. Fasting plasma glucose =7.0 mmol/l (=126 mg/dl).
Fasting is defined as no caloric intake for at least 8 h.
3. 2-hour postload glucose =11.1 mmol/l (=200 mg/dl) during an
OGTT
The test should be performed as described by WHO,
1999, using a glucose load containing the equivalent of 75 g anhydrous
glucose dissolved in water or 1.75 g/kg of body weight to a maximum of 75 g
(Rasilainen et al., 2004).
Corresponding values (mmol/L) are =10.0 for venous whole blood
=11.1 for capillary whole blood and =6.3 for both venous and capillary whole
blood.
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