Diabetic Complications: Acute & Chronic
Diabetes Mellitus causes systemic damage primarily through nonenzymatic glycosylation (HbA1c formation) and the polyol pathway (sorbitol accumulation).
1. Acute Life-Threatening States
| Feature | DKA (Type 1) | HHS (Type 2) |
|---|---|---|
| Glucose | >250 mg/dL | >600 mg/dL |
| Ketones | Positive (high) | Negative/trace |
| Acidosis | Severe (pH < 7.3) | Absent (pH > 7.3) |
2. Chronic Macro/Microvascular Damage
- Macrovascular: Accelerated atherosclerosis leading to coronary artery disease, peripheral vascular disease, and stroke.
- Microvascular:
- Nephropathy: Kimmelstiel-Wilson nodules (nodular glomerulosclerosis); diffuse thickening of the GBM.
- Retinopathy: Microaneurysms, “cotton-wool” spots, and neovascularization.
- Neuropathy: Symmetrical “stocking-glove” distribution; risk of foot ulcers and osteomyelitis.
Pathology Board Hint: Always recall the polyol pathway: Glucose is converted to sorbitol by aldose reductase. Sorbitol causes osmotic damage in the lens (cataracts), retina, kidneys, and Schwann cells (neuropathy). If the patient is Type 1 and presents with Kussmaul respirations (deep, rapid breathing), think DKA.