What bloodwork is recommended for a patient with diabetes and chronic dizziness?

Recommended Bloodwork for Patients with Diabetes and Chronic Dizziness

For patients with diabetes and chronic dizziness, comprehensive bloodwork should include HbA1c, fasting plasma glucose, complete blood count, comprehensive metabolic panel, lipid profile, and orthostatic blood pressure measurements to evaluate both glycemic control and potential causes of dizziness.

Core Diabetes Monitoring Tests

Glycemic Control Assessment

• HbA1c: Essential for evaluating long-term glycemic control 1
  • Target: Generally ≤7% for most patients
  • Should be performed in an NGSP-certified laboratory 2
• Fasting Plasma Glucose (FPG):
  • Should be drawn after at least 8 hours of fasting 2
  • Important collection considerations:
    • Place sample immediately in ice-water slurry and separate plasma within 30 minutes
    • Alternatively, use tubes containing citrate buffer as glycolysis inhibitor 2

Lipid Profile

• Should be measured at least annually in most adults with diabetes 2
• More frequent testing may be needed if abnormal or if medication changes
• Include:
  • Total cholesterol
  • LDL cholesterol
  • HDL cholesterol
  • Triglycerides
• Can be performed every 2 years if values are at low-risk levels (LDL <100 mg/dL, HDL >50 mg/dL, triglycerides <150 mg/dL) 2

Additional Tests for Dizziness Evaluation

Complete Blood Count (CBC)

• Essential to evaluate for anemia, which can cause dizziness
• Particularly important as certain anemias can affect HbA1c interpretation 2

Comprehensive Metabolic Panel

• Electrolytes (sodium, potassium, chloride, bicarbonate)
  • Electrolyte imbalances can contribute to dizziness
• Renal function (BUN, creatinine)
  • Important to assess diabetic nephropathy and medication effects
• Liver function tests
  • May affect medication metabolism

Specific Tests for Orthostatic Hypotension

• Orthostatic blood pressure measurements (lying/sitting and standing)
  • Postural hypotension is common in diabetes and associated with dizziness 3
  • Defined as a decline of ≥20 mmHg in systolic blood pressure upon standing
  • Research shows higher prevalence of postural hypotension in diabetic patients 3

Considerations for Test Interpretation

1. HbA1c Limitations:

   • May be affected by certain hemoglobinopathies and anemias 2
   • For patients with abnormal hemoglobin but normal red cell turnover, use an assay without interference from abnormal hemoglobins 2

2. Glucose Testing Precautions:

   • Pre-analytical stability is critical for accurate glucose measurements
   • Glycolysis can significantly affect results if proper handling procedures aren't followed 2

3. Integrated Assessment:

   • Consider both diabetes control and dizziness etiology when interpreting results
   • Poor glycemic control (elevated HbA1c and glucose levels) is independently associated with postural hypotension 3

Follow-up Testing

• If initial testing doesn't reveal a clear cause, consider:
  • Vestibular function tests if vertigo is present
  • Cardiac evaluation (ECG, Holter monitoring) if presyncope is the predominant symptom
  • Neurological evaluation if disequilibrium is the main complaint 4

Remember that dizziness in diabetic patients may be multifactorial, with contributions from autonomic neuropathy, medication effects, and other comorbidities. The bloodwork provides essential information but should be interpreted in the context of the patient's clinical presentation.