What are the causes and treatment options for acute diabetes mellitus?

Causes of Acute Diabetes Mellitus

The primary causes of acute diabetes mellitus include autoimmune destruction of pancreatic beta cells (Type 1), acute illness triggering diabetic ketoacidosis, and immune checkpoint inhibitor therapy causing autoimmune diabetes. These conditions require prompt recognition and treatment to prevent life-threatening complications 1, 2.

Types of Acute Diabetes Presentations

1. Type 1 Diabetes (T1D)

• Pathophysiology: Autoimmune destruction of β-pancreatic cells leading to insulinopenia 1
• Onset: Can develop rapidly over hours to days
• Key feature: Insulin deficiency results in diabetic ketoacidosis (DKA) within a few hours if untreated 1
• Clinical presentation:
  • Polyuria, polydipsia, unexplained weight loss
  • Plasma glucose ≥2 g/L (11.1 mmol/L) regardless of timing
  • Fasting blood glucose ≥1.26 g/L (7.0 mmol/L) on two occasions 1

2. Diabetic Ketoacidosis (DKA)

• Characteristics: Plasma glucose >250 mg/dl, arterial pH <7.30, serum bicarbonate <15 mEq/l, significant ketones in urine and blood 2
• Common precipitating factors:
  • Infection (most common)
  • Recent onset or discontinuation/inadequate administration of insulin
  • Stroke, alcohol abuse, pancreatitis, myocardial infarction, trauma
  • Medications affecting carbohydrate metabolism (corticosteroids, thiazides, sympathomimetic agents) 2

3. Checkpoint Inhibitor-Associated Diabetes Mellitus (CIADM)

• Mechanism: Presumed autoimmune pathophysiology similar to sporadic Type 1 diabetes 1
• Presentation: Acute onset of polyuria, polydipsia, weight loss, and lethargy
• Risk: Can rapidly progress to DKA requiring immediate intervention 1
• Distinguishing feature: Occurs in patients receiving immune checkpoint inhibitor therapy for cancer treatment

4. Stress Hyperglycemia

• Definition: Transient hyperglycemia in previously non-diabetic patients experiencing acute illness or undergoing invasive procedures 1
• Severity: Depends on type of surgery, aggressiveness of procedure, and duration
• Mechanism: Leads to peripheral insulin resistance
• Significance: Independent prognostic factor for morbidity and mortality 1

Diagnostic Approach

For patients presenting with acute hyperglycemia, investigations should determine whether the condition is:

1. Pre-existing diabetes with acute exacerbation
2. New-onset Type 1 diabetes
3. Stress hyperglycemia
4. Medication-induced diabetes 1

Key diagnostic tests include:

• Fasting blood glucose and/or random blood glucose
• HbA1c
• Urine or blood ketones
• Arterial blood gases (if DKA suspected)
• Antibody testing (anti-GAD, anti-insulin) for suspected autoimmune diabetes 1, 2

Management of Acute Hyperglycemic Emergencies

For Diabetic Ketoacidosis:

1. Fluid replacement: Correct dehydration
2. Insulin therapy: Administer intravenous insulin
   • Initial bolus of regular insulin followed by continuous infusion
3. Electrolyte replacement: Monitor and correct imbalances
4. Identify and treat precipitating factors 2

For Checkpoint Inhibitor-Associated Diabetes:

• Initiate insulin therapy immediately
• Do not delay treatment pending antibody results
• Obtain endocrinology consultation
• Consider hospitalization if outpatient endocrinology not readily available 1

For Acute Illness in Known Diabetics:

• Continue insulin: Never omit insulin during acute illness in Type 1 diabetes 1
• Increase monitoring: Test blood glucose and ketones frequently
• Maintain hydration: Increase fluid intake to prevent dehydration
• Ensure carbohydrate intake: 150-200g carbohydrate daily (45-50g every 3-4 hours) to prevent starvation ketosis 1
• Adjust insulin: Additional insulin may be required due to stress-induced counterregulatory hormones 1

Prevention of Acute Complications

• Education: Teach patients about risk factors for hyperglycemic emergencies
• Sick-day management: Provide detailed instructions on insulin adjustment during illness
• Early intervention: Contact diabetes care team immediately if DKA is suspected
• Ketone monitoring: Measure ketones in urine or blood when glucose exceeds 200 mg/dL 2

Common Pitfalls to Avoid

1. Delayed recognition of autoimmune diabetes in patients on immune checkpoint inhibitors
2. Misdiagnosing CIADM as worsening of type 2 diabetes
3. Omitting insulin during acute illness in type 1 diabetes patients
4. Inadequate fluid replacement during treatment of hyperglycemic emergencies
5. Failing to monitor for hypoglycemia during treatment of hyperglycemic crisis

Remember that acute diabetes presentations, particularly those involving ketoacidosis, are medical emergencies requiring prompt intervention to reduce morbidity and mortality.