Question

Write the laboratory investigations required to establish a case of diabetes.

Hint:

An HbA1c reading of $5.7\%$ to $6.4\%$ indicates prediabetes, showing that the patient is at high risk of developing Type II diabetes. This stage can often be reversed through diet, exercise, and weight loss.

Answer 1

Step 1: Diagnostic Objectives:
To establish a definitive diagnosis of diabetes mellitus, clinical laboratory tests must demonstrate persistent, chronic hyperglycemia (high blood sugar levels) using standardized biochemical criteria.

Step 2: Key Diagnostic Laboratory Tests:
The standard blood tests used to diagnose diabetes are:

• Fasting Plasma Glucose (FPG) Test: Measures blood glucose levels after an overnight fast of at least $8\text{ hours}$.
  • Normal: $< 100\text{ mg/dL}$
  • Prediabetes: $100\text{ mg/dL to } 125\text{ mg/dL}$
  • Diabetes: $\ge 126\text{ mg/dL$}
• Oral Glucose Tolerance Test (OGTT): Measures blood glucose levels before and $2\text{ hours}$ after drinking a standardized sweet beverage containing $75\text{ grams}$ of anhydrous glucose dissolved in water.
  • Normal: $< 140\text{ mg/dL}$
  • Prediabetes: $140\text{ mg/dL to } 199\text{ mg/dL}$
  • Diabetes: $\ge 200\text{ mg/dL$}
• Glycated Hemoglobin (HbA1c) Test: Measures the average percentage of hemoglobin bound to glucose over the past $8\text{ to }12\text{ weeks}$, offering a reliable indicator of long-term glycemic control.
  • Normal: Below $5.7\%$
  • Prediabetes: $5.7\%$ to $6.4\%$
  • Diabetes: $\ge 6.5\%$
• Random Casual Plasma Glucose Test: Measures blood glucose at any time of day, regardless of meals. A reading of $\ge 200\text{ mg/dL$}, combined with classic symptoms of diabetes (such as polyuria, polydipsia, and unexplained weight loss), is sufficient to diagnose diabetes.

Step 3: Supplementary Urine Tests:
Urine analyses can also detect glycosuria (glucose spilling into the urine) and ketonuria (ketones in the urine, indicating diabetic ketoacidosis).