Diabetes Types - Type 1 & Type 2

Presentation notes on Diabetes Mellitus Classifications, Types, Insulin Deficiency  & Drugs for Medical & Biology Students in PPT / word / .doc Format  

CLASSIFICATION OF DIABETES MELLITUS

Although all forms of diabetes mellitus share hyperglycemia as a common feature, the pathogenic processes involved in the development of hyperglycemia vary widely. The previous classification schemes of diabetes mellitus were based on the age at onset of the disease or on the mode of therapy ; in contrast, the recently revised classification reflects our greater understanding of the pathogenesis of each variant. The vast majority of cases of diabetes fall into one of two broad classes :

Type 1 :         Diabetes is characterized by an absolute deficiency of insulin

caused by pancreatic b cell destruction. It accounts for approximately 10% of all cases.

Type 2 :       Diabetes is caused by a combination of peripheral resistance to insulin action and inadequate secretory response by the pancreatic b cells. Approximately 80% to 90% of patients have type 2 diabetes.

    

A variety of monogenic and secondary causes are responsible for the remaining cases. It should be stressed that while the major types of diabetes have different pathogenic mechanisms, the long – term complications in kidneys, eyes, nerves, and blood vessels are the same, as are the principal causes of morbidity and death. The pathogenesis of the two major types is discussed separately.

1. Type 1diabetes (b cell destruction, leads to absolute insulin deficiency)

• Immune mediated
• Idiopathic

2. Type 2 diabetes (insulin resistance with relative insulin deficiency).

3. Genetic defects of b cell function.

  

• Maturity onset diabetes of the young (MODY), caused by mutations in :

-          Hepatocyte nuclear factor 4a (HNF – 4a) (MODY3).

-          Glucokinase (MODY2).

-          Hepatocyte nuclear factor 1a (HNF - 1a) (MODY5).

-          Insulin promoter factor 1b (HNF - 1b) (MODY5).

-          Hepatocyte nuclear factor 1b (HNF- 1b) (MODY5)

-          Neurogenic differentiation factor 1 (Neuro D1) (MODY6).           

• Mitochondrial DNA mutations.

4. Genetic defects in insulin processing or insulin action

  

• Defects in proinsulin conversion.
• Insulin gene mutations.
• Insulin receptor mutations.

5. Exocrine pancreatic defects.

• Chronic pancreatitis
• Pancreatectomy
• Neoplasia
• Cystic fibrosis
• Hemachromatosis
• Fibrocalculous pancreatopathy.

6. Endocrinopathies

• Acromegaly
• Cushing syndrome
• Hyperthyroidism
• Pheochromocytoma
• Glucagonoma.

7. Infections

• Cytomegalovirus
• Coxackie virus B.

8. Drugs

• Glucocorticoids
• Thyroid hormone
• a - interferon
• Protease inhibitors
• b - adrenergic agonists
• Thiazides
• Nicotinic acid
• Phenytoin.

9. Genetic syndromes associated with diabetes

 

• Down syndrome
• Kleinfelter syndrome
• Turner syndrome.

10.Gestational diabetes mellitus

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