Endocrine Pathology

Question 1

What are the clinical differences between type 1 and type 2 DM?

Answer 1

Type 1: 
• Onset - childhood & adolescence
• Normal weight or LOW before diagnosis
• Progressive decrease in insulin levels
• Circulating islet cell auto-Abs
• DKA in absence of insulin therapy
Type 2:
• Onset - adult
• Majority obese (80%)
• Increased blood insulin (early); normal or moderate decrease in insulin (late)
• No islet auto-Abs
• NKHC more common

Question 2

Describe the differences in pathogenesis of type 1 and type 2 DM

Answer 2

Type 1:
• Autoimmune B-islet cell destruction
• Involves genetic susceptibility (major linkage to MHC class I and II genes) and environmental insults (viruses implicated include coxsackie, mumps, CMV)
• Dysfunction in regulatory T cells leading to breakdown in self-tolerance to islet auto-Ags
• Insulitis, B-cell depletion and islet atrophy
Type 2:
• Multifactorial disease
• No HLA linkage but genetic susceptibility
• Insulin resistance in peripheral tissues and failure of compensation by B-cells (dysfunction)
• Multiple obesity-associated factors linked to pathogenesis of insulin resistance
• No insulitis, amyloid deposition in islets, mild B-cell depletion