9. Diabetes mellitus – pathobiochemistry – alterations in carbohydrate, protein and lipid metabolism. Mechanisms of development of the acute and chronic complications.

Manifestations of diabetes

• Type 1 → signs and symptoms arise suddenly
• Type 2 → develops insidiously
• The most commonly identified signs and symptoms are:

1. Hyperglycemia
2. Glycosuria (presence of glucose in the urine)
3. Three polyps

• Polyuria (excessive urination)
• Glucose is a small, osmotically active molecule
• When blood glucose levels are sufficiently elevated, the amount of glucose filtered by the glomeruli of the kidney exceeds the amount that can be reabsorbed by the renal tubules
• This results in glycosuria accompanied by large losses of water in the urine
• Polydipsia (excessive thirst)
• Results from the intracellular dehydration that occurs as blood glucose levels rise and water is pulled out of body cells, including those of the thirst centre
• Cellular dehydration also causes dryness of the mouth
• Polyphagia (excessive hunger)
• Not usually present in people with type 2 diabetes
• In type 1 diabetes, it probably results from cellular starvation and the depletion of cellular stores of carbohydrates, fats, and proteins

4. Weight loss

a) Fluid loss

• Results from osmotic diuresis
• Exaggerated by vomiting in ketoacidosis

b) Body tissue loss

• Lack of insulin forces the body to use its fat stores and cellular proteins as energy source

5. Blurred vision

• Lens and retina are exposed to hyperosmotic effects of elevated blood glucose levels → swelling → disrupted vision

6. Fatigue
7. Skin infections

• Common in type 2 diabetes
• Hyperglycemia and glycosuria favour the growth of yeast organisms

8. Poor wound healing