Diabetes Mellitus Type 1 and Type 2

(a) Type 1 Diabetes Mellitus (T1DM):

Type 1 diabetes is an autoimmune condition where the body’s immune system mistakenly attacks and destroys insulin-producing β cells in the pancreas. This leads to a significant reduction or complete absence of insulin production, which is essential for regulating blood glucose levels. T1DM typically manifests in childhood or adolescence but can occur at any age. The exact cause is not fully understood, but it involves a combination of genetic predisposition and environmental triggers, such as viral infections. Patients with T1DM require lifelong insulin therapy to manage their blood sugar levels effectively.

Key characteristics of T1DM include:

• Sudden onset of symptoms such as excessive thirst (polydipsia), frequent urination (polyuria), unexplained weight loss, fatigue, and blurred vision.
• Dependence on exogenous insulin for survival.
• Risk of diabetic ketoacidosis (DKA), a life-threatening complication caused by severe insulin deficiency leading to high blood glucose and ketone production.

(b) Type 2 Diabetes Mellitus (T2DM):

Type 2 diabetes results from a combination of insulin resistance (where the body’s cells do not respond effectively to insulin) and inadequate compensatory insulin secretion by pancreatic β cells. Unlike T1DM, T2DM is more commonly associated with lifestyle factors such as obesity, physical inactivity, and poor diet, although genetic predisposition also plays a role. It typically develops in adults over 45 years old but is increasingly being diagnosed in younger individuals due to rising obesity rates.

Key characteristics of T2DM include:

• Gradual onset of symptoms that may go unnoticed for years.
• Insulin resistance as a primary feature, often accompanied by hyperglycemia.
• Management through lifestyle modifications (diet and exercise), oral medications like metformin, and sometimes insulin therapy if necessary.

Complications of Diabetes

Both type 1 and type 2 diabetes can lead to acute and chronic complications if poorly managed:

Acute Complications

1. Hypoglycemia:
   Caused by excessive insulin administration or insufficient food intake relative to medication/exercise. Symptoms include shakiness, sweating, confusion, seizures, or even coma if untreated.

3. Diabetic Ketoacidosis (DKA):
   Primarily seen in T1DM due to severe insulin deficiency. It results in hyperglycemia (>250 mg/dL), ketonemia/ketonuria, metabolic acidosis (pH <7.3), dehydration, nausea/vomiting, abdominal pain, and altered mental status.
4. Hyperosmolar Hyperglycemic State (HHS):
   More common in T2DM; characterized by extreme hyperglycemia (>600 mg/dL) without significant ketosis but with severe dehydration and altered consciousness.

Chronic Complications

Chronic hyperglycemia damages blood vessels and tissues over time:

Microvascular Complications:

• Diabetic Retinopathy: Damage to retinal blood vessels leading to vision impairment or blindness.
• Diabetic Nephropathy: Kidney damage resulting in proteinuria and eventual kidney failure.
• Diabetic Neuropathy: Nerve damage causing numbness/pain in extremities or autonomic dysfunction affecting digestion or cardiovascular regulation.

Macrovascular Complications:

• Cardiovascular Disease: Increased risk of heart attack, stroke, hypertension, and atherosclerosis.
• Peripheral Artery Disease: Poor circulation leading to ulcers or gangrene requiring amputation.

Other Complications:

• Increased susceptibility to infections due to impaired immune response.
• Diabetic foot ulcers caused by neuropathy combined with poor wound healing.

Islet Cell Tumors

Islet cell tumors are rare neoplasms arising from the endocrine pancreas’s islets of Langerhans. These tumors can be benign or malignant and are classified based on their hormone secretion profile:

Functional Islet Cell Tumors

These tumors secrete hormones excessively:

1. Insulinomas:
   • Secrete excess insulin causing recurrent hypoglycemia.
   • Symptoms include confusion, sweating, tremors, seizures during fasting states.
   • Diagnosed via fasting glucose tests showing low blood sugar with high serum insulin levels.

2. Gastrinomas (Zollinger-Ellison Syndrome):
   • Overproduce gastrin leading to excessive stomach acid production.
   • Causes peptic ulcers resistant to standard treatment.

3. Glucagonomas:
   • Secrete glucagon causing hyperglycemia along with characteristic skin rash called necrolytic migratory erythema.

4. VIPomas:
   • Produce vasoactive intestinal peptide leading to watery diarrhea syndrome known as WDHA syndrome (Watery Diarrhea Hypokalemia Achlorhydria).

5. Somatostatinomas:
   • Rare tumors secreting somatostatin causing diabetes-like symptoms due to inhibition of other hormones like glucagon/insulin.

Nonfunctional Islet Cell Tumors

These do not secrete hormones actively but may grow large enough to cause mass effects like abdominal pain or obstruction before detection.

Diagnosis and Treatment

Diagnosis involves imaging studies such as CT/MRI scans combined with biochemical tests measuring hormone levels specific to the tumor type. Treatment options include surgical resection for localized tumors or systemic therapies like chemotherapy for metastatic disease.