Page 572 - Concise Pathology for Exam Preparation ( PDFDrive )

20 Endocrinology 557

Aetiologic classification of DM (as per American Diabetes Association):
1. Type I DM (10% incidence); earlier called IDDM or juvenile-onset diabetes:
Contrary to its earlier name, this can manifest at any age and is associated with b-cell
destruction and absolute insulin deficiency. It is classified into two subtypes.

Type I Diabetes mellitus

Type IA DM (Immune mediated) Type IB DM (Idiopathic)
2. Type II DM (80% incidence); earlier called NIDDM is associated with insulin resis-
tance and relative insulin deficiency.
3. Genetic defects in b-cell function
(a) Genetic defect of b-cell function due to mutations in various enzymes-hepatocyte
nuclear factor 4a, MODY1, glucokinase, MODY2; earlier called maturity onset
diabetes of young or MODY.
(b) Neonatal diabetes (activating mutations in KCNJ11 and ABCC8 encoding Kir6.2
and SUR1, respectively).
(c) Maternally inherited diabetes and deafness (MIDD) due to mitochondrial DNA muta-
tions
(d) Defects in proinsulin conversion
(e) Insulin gene mutations
4. Genetic defects in insulin action
(a) Type A insulin resistance
(b) Lipoatrophic diabetes
5. Exocrine pancreatic defects
(a) Chronic pancreatitis
(b) Pancreatectomy/trauma
(c) Neoplasia
(d) Cystic fibrosis
(e) Haemochromatosis
(f) Fibrocalculous pancreatopathy
6. Endocrinopathies
(a) Acromegaly
(b) Cushing syndrome
(c) Hyperthyroidism
(d) Pheochromocytoma
(e) Glucagonoma
7. Infections
(a) Cytomegalovirus
(b) Coxsackie B virus
(c) Congenital rubella
8. Drugs
(a) Glucocorticoids
(b) Thyroid hormone
(c) Interferon a
(d) b adrenergic agonists
(e) Thiazides
(f) Nicotinic acid
(g) Phenytoin
9. Genetic syndromes associated with diabetes
(a) Down syndrome
(b) Klinefelter syndrome
(c) Turner syndrome
(d) Prader Willi syndrome

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