history. The stages reflect various degrees of hyperglycemia in individual subjects even in absence of underlying etiology.

I . Type 1 Diabetes (b-cell destruction, usually leading to bsolute insulin deficiency)
       A. Immune mediated
       B. Idiopathic
I I . T ype 2 Diabetes (may range from predominantly insulin resistance with relative insulin deficiency to a predominantly secretory defect with insulin resistance)
I I I . Gestational Diabetes Mellitus
I V . Other specific types
A. Genetic defects of b-cell function
   1. Chromosome 12, HNF -1            (MODY3)
   2. Chromosome 7, glucokinase           (MODY2)
   3. Chromosome 20, HNF -4           (MODY1)
   4. Chromosome 13, insulin           promoter factor-1 (IP F -1;          MODY4)
   5. Chromosome 17, HNF -1b         (MODY5)
   6. Chromosome 2, NeuroD1         (MODY6)
    7. Mitochondrial DNA
    8. Others
B. Genetic defects in insulin action
    1. Type A insulin resistance
    2. Leprechaunism
    3. R abson-Mendenhall syndrome
    4. Lipoatrophic Diabetes
    5. Others
C. Diseases of the exocrine          pancreas
     1. P ancreatitis
     2. Trauma / P ancreatectomy
     3. Neoplasia
     4. Cystic fibrosis
     5. Hemochromatosis
     6. ibrocalculous pancreatopathy
     7. Others
D. E ndocrinopathies
     1. Acromegaly
     2. CushingÕs syndrome
       3. Glucagonoma
    4. Pheochromocytoma
    5. Hyperthyroidism
    6. S omatostatinoma
    7. Aldosteronoma
    8. Others
E . Drug or chemical-induced
    1. Vacor
    2. P entamidine
    3. Nicotinic acid
    4. Glucocorticoids
    5. Thyroid hormone
    6. Diazoxide
    7. b-adrenergic agonists
    8. Thiazides
    9. Dilantin
    10. a-Interferon
    11. Others
F . Infections
    1. Congenital rubella
    2. Cytomegalovirus
    3. Others
G. Uncommon forms of immune mediated Diabetes
    1. "S tiff-man" syndrome
    2. Anti-insulin receptor        antibodies
    3. Others
H. Other genetic syndromes sometimes associated with Diabetes
    1. DownÕs syndrome
    2. KlinefelterÕs syndrome
    3. TurnerÕs syndrome
    4. WolframÕs syndrome
    5. F riedreichÕs ataxia
    6. HuntingtonÕs chorea
    7. Laurence-Moon-Biedl         syndrome
    8. Myotonic dystrophy
    9. Porphyria
    10. P rader-Willi syndrome
Table 2 : WHO classification of Diabetes Mellitus

GESTATIONAL DIABETES MELLITUS (GDM)
It is carbohydrate intolerance associated with hyperglycaemia of variable severity (IFG, IGT or DM) with the onset or first recognition during pregnancy.
Glucose Challenge test is conducted between 24-28 weeks of pregnancy. Irrespective of previous need, the subject is given an oral glucose drink of 50 gm glucose. Blood glucose is determined 60 minutes after the glucose drink. Value of 7.8 mmol is considered positive. The subject is then referred for OGTT and any degree of carbohydrate intolerance (IFG, IGT or DM) detected is GDM.

CLINICAL FEATURES
The most easily recognized symptoms are secondary to hyperglycemia, glycosuria and ketoacidosis.

   ●  Hyperglycemia: Hyperglycemia alone may not cause obvious symptoms, although some patient reported general malaise, headache & weakness. They may also appear irritable and become ill tempered.
   ●  Glycosuria: This condition leads to increased urinary frequency and volume (eg, polyuria), which is particularly troublesome at night (eg, nocturia).
   ●   Polydipsia: Increased thirst, which may be insatiable, is secondary to the osmotic diuresis causing dehydration.
   ●  Weight loss: Insulin deficiency leads to uninhibited gluconeogenesis, causing breakdown of protein and fat. Weight loss may be dramatic, even though the appetite
usually remains good.

  Symptoms of ketoacidosis
        ● Severe dehydration
        ● Smell of ketones
        ● Acidotic breathing (ie, Kussmaul respiration)
        ● Abdominal pain
        ● Vomiting
        ● Drowsiness and coma
  
Other nonspecific findings
        ● Hyperglycemia impairs immunity & more susceptible to recurrent             infection, particularly of the urinary tract, skin & respiratory tract.
        ● Candidiasis may develop, especially in groin and flexural areas.

 

 

 

DISORDERS OF GLYCAEMIA
Etiological types and clinical stages of glycaemia is given in table 3.

 

 

 

A.  Normoglycaemia - Individuals with FPG less than 6.1 mmol/      (llOmg/dl) has been chosen as "normal". Some of these individuals      may have recognizable pathological or aetiological processes      despite a normal glucose tolerance. Again some may have IGT.
B.  Impaired glucose regulation (IGT and IFG) represents a metabolic      state intermediate between normal glucose homeostasis and      diabetes. IFG and IGT represent different abnormalities of glucose      regulation, one in the fasting state (IFG) and the other in the      post- parandial state (IGT). IGT is categorized as a stage in the      natural history of diabetes mellitus rather than being a separate      class. IFG is recognized because these subjects like those with IGT      have increa sed risk of progressing to diabetes and macrovascular     disease, but perhaps at a lower risk of progression than IGT     subjects.
C  .Diabetes Mellitus - Regardless of underlying cause may be      subdi vided into:
     1.   Insulin requiring for survival (formerly IDDM) - Type I diabetes
     2   .Insulin requiring for control in order to achieve metabolic control            rather than for survival.
     3. Not insulin requiring: satisfactory control achieved with diet,           exercise and or drugs, but not insulin.