Overview

• Also called insulin-dependent diabetes mellitus (IDDM).
• Formerly known as juvenile diabetes due to early onset, typically during childhood.
• Less common than Type II, accounting for about 10% of diabetes cases.
• Usually more severe because of acute complications if blood glucose is not well-controlled.
• Body weight: Usually thin due to increased catabolism caused by lack of insulin.

Causes

• Autoimmune destruction of pancreatic beta cells in the islets of Langerhans.
• Leads to little or no insulin production.
• Thought to be triggered by several possible factors:
  • Viral exposures: Epstein-Barr virus, cytomegalovirus, mumps.
  • Genetics: Runs in families (family history)
  • Geographic factors: Higher prevalence away from the equator, e.g., Finland.
  • Not linked to obesity (unlike Type II).

Typical Onset:

• Rapid development in children.
• Can occur in adults as a latent autoimmune diabetes variant.

Pathophysiology:

• Lack of insulin prevents glucose entry into cells,
  • as cell’s require insulin to insert GLUT4 glucose transporters into their cell membranes.
  • leading to high blood glucose levels (hyperglycemia).
• Cells become starved for glucose, impairing ATP production.
• Excess glucose diffuses into urine, drawing water and causing polyuria, causing
• Dehydration triggers thirst (polydipsia).
• The body responds by breaking down proteins and fats for energy:
  • Gluconeogenesis: Produces glucose from proteins and fats.
  • Lipolysis: Leads to high lipid levels (lipidemia).

Effects on the Body

• Muscle wasting due to protein breakdown.
• High blood lipids increase risk of atherosclerosis.
• Ketone production causes ketosis and potentially ketoacidosis:
  • Blood becomes acidic.
  • Ketones and glucose are excreted in urine (ketonuria and glucosuria).

Signs and Symptoms:

• Polydipsia:  Increased thirst (due to dehydration)
• Polyphagia:  Increased hunger
• Polyuria:  Increased urine volume (due to glucosuria and osmotic diuresis)
• Fatigue (due to cell’s reduced ability to uptake glucose)
• Blurred vision (due to retinopathies and diabetic cataracts)
• Slowed healing of wounds (due to cell’s reduced ability to uptake glucose)

Diagnostic Blood Tests:

1. Glycated hemoglobin (A1c) test
   • Measures the percentage of hemoglobin with blood sugar attached.
   • Reflects blood glucose control over 2-3 months.
   • Levels above 6.5% suggest diabetes.
2. Random blood sugar test
   • Blood sample taken randomly, regardless of fasting.
   • Blood glucose above 110 mg/dL indicates abnormality.
3. Fasting blood sugar test
   • Fasting for 12 hours before testing.
   • Normal: <100 mg/dL.
   • Diabetic: >125 mg/dL.

Treatments:

• Insulin injections are essential.
• No known preventive cause or cure; management focuses on blood sugar control.
  • Note:  Pancreatic transplants are challenging, and are not curative as the underlying cause of autoimmune destruction of the pancreatic beta cells by auto-antibodies and WBCs still exists.

Complications of Uncontrolled Diabetes and Risk of Long-Term Damage:

• Blood vessel damage leads to:
  • Atheromas formation.
  • Vascular damage affecting organs. and putting person at risk for:
    • Cardiovascular disease: Stroke, heart attack, peripheral vascular disease.
    • Kidney failure (due to nephropathy).
    • Nerve damage: Neuropathy
    • Pregnancy complications: Stillbirths and miscarriages.
    • Increased risk of amputations due to ischemia and gangrene.
    • Eye damage: Leading to blindness (diabetic retinopathy).

• Blurred Vision or Vision Loss: 
  • also due to development of diabetic (sugar) cataracts

Summary

• In Type I, autoimmune destruction results in insulin deficiency.
• Autoimmune origin causes destruction of beta cells in pancreatic islets of Langerhans.
• Blood glucose regulation is severely impaired.
• Rapid onset in children, generally non-obese.
• Requires lifelong insulin therapy.
• Precursors and triggers are still under study.
• The condition leads to vascular damage affecting multiple organs and systems, emphasizing the importance of tight blood glucose control.