Diabetes Mellitus: Types and Pathophysiology

Definition and Classification

• Diabetes mellitus is a group of metabolic disorders characterized by high blood sugar levels (hyperglycemia) due to defects in insulin secretion, insulin action, or both.
• Classified into two main types:
  • Type 1 diabetes (T1D): beta-cell destruction, usually leading to absolute insulin deficiency
  • Type 2 diabetes (T2D): insulin resistance, impaired insulin secretion, and increased glucose production

Pathophysiology

• Normal glucose metabolism:
  • Insulin stimulates glucose uptake in cells
  • Glucagon stimulates glucose release from storage
• In diabetes:
  • Insulin deficiency or resistance leads to hyperglycemia
  • Increased glucose production in the liver
  • Impaired glucose uptake in peripheral tissues

Causes and Risk Factors

• Type 1 diabetes:
  • Genetic predisposition
  • Autoimmune destruction of beta-cells
• Type 2 diabetes:
  • Obesity and physical inactivity
  • Insulin resistance
  • Family history
  • Age (>45 years)
  • Ethnicity (African American, Hispanic, American Indian)

Symptoms

• Common symptoms:
  • Polyuria (excessive urination)
  • Polydipsia (excessive thirst)
  • Polyphagia (excessive hunger)
  • Fatigue
  • Blurred vision
  • Slow healing of cuts and wounds
• May be asymptomatic in early stages

Diagnosis

• Diagnostic criteria:
  • Fasting plasma glucose ≥ 126 mg/dL
  • 2-hour plasma glucose ≥ 200 mg/dL during an oral glucose tolerance test
  • Hemoglobin A1c (HbA1c) ≥ 6.5%
• Additional tests:
  • Urine test for ketones (in T1D)
  • Autoantibody tests (in T1D)

Complications

• Acute:
  • Diabetic ketoacidosis (DKA)
  • Hypoglycemia
• Chronic:
  • Microvascular complications:
    • Retinopathy
    • Nephropathy
    • Neuropathy
  • Macrovascular complications:
    • Cardiovascular disease
    • Peripheral artery disease
    • Stroke

Management

• Lifestyle modifications:
  • Healthy diet
  • Regular physical activity
  • Weight loss (if overweight)
• Pharmacological interventions:
  • Insulin therapy (in T1D and some T2D cases)
  • Oral antidiabetic agents (in T2D)
  • Injectable medications (in T2D)
• Monitoring and surveillance:
  • Regular blood glucose monitoring
  • HbA1c monitoring
  • Screening for complications

Definition and Classification

• Diabetes mellitus is a group of metabolic disorders characterized by high blood sugar levels (hyperglycemia) due to defects in insulin secretion, insulin action, or both.
• Classified into two main types: Type 1 diabetes (T1D) and Type 2 diabetes (T2D).

Pathophysiology

• In normal glucose metabolism, insulin stimulates glucose uptake in cells, and glucagon stimulates glucose release from storage.
• In diabetes, insulin deficiency or resistance leads to hyperglycemia, increased glucose production in the liver, and impaired glucose uptake in peripheral tissues.

Causes and Risk Factors

• Type 1 diabetes is caused by genetic predisposition and autoimmune destruction of beta-cells.
• Type 2 diabetes is caused by obesity and physical inactivity, insulin resistance, family history, age (>45 years), and ethnicity (African American, Hispanic, American Indian).

Symptoms

• Common symptoms of diabetes include polyuria (excessive urination), polydipsia (excessive thirst), polyphagia (excessive hunger), fatigue, blurred vision, and slow healing of cuts and wounds.
• Diabetes may be asymptomatic in early stages.

Diagnosis

• Diagnostic criteria for diabetes include fasting plasma glucose ≥ 126 mg/dL, 2-hour plasma glucose ≥ 200 mg/dL during an oral glucose tolerance test, and hemoglobin A1c (HbA1c) ≥ 6.5%.
• Additional tests for diabetes diagnosis include urine test for ketones (in T1D) and autoantibody tests (in T1D).

Complications

• Acute complications of diabetes include diabetic ketoacidosis (DKA) and hypoglycemia.
• Chronic complications of diabetes include microvascular complications (retinopathy, nephropathy, neuropathy) and macrovascular complications (cardiovascular disease, peripheral artery disease, stroke).

Management

• Lifestyle modifications for diabetes management include healthy diet, regular physical activity, and weight loss (if overweight).
• Pharmacological interventions for diabetes management include insulin therapy (in T1D and some T2D cases), oral antidiabetic agents (in T2D), and injectable medications (in T2D).
• Monitoring and surveillance for diabetes management include regular blood glucose monitoring, HbA1c monitoring, and screening for complications.