Next Step: Confirm the Diagnosis with Repeat Testing
The first next step is to repeat the fasting blood glucose test on a subsequent day to confirm whether this patient has diabetes, prediabetes, or normal glucose metabolism (Option A). 1, 2
Why Confirmation Testing is Mandatory
A single glucose measurement of 7.2 mmol/L (approximately 130 mg/dL) meets the fasting plasma glucose criterion for diabetes (≥7.0 mmol/L or ≥126 mg/dL), but standard diagnostic protocols mandate confirmation by repeat testing before establishing the diagnosis. 1, 2
The American Diabetes Association explicitly states that in the absence of unequivocal hyperglycemia (random glucose ≥11.1 mmol/L with classic symptoms) or hyperglycemic crisis, any diagnostic test result must be confirmed by repeat testing on a different day to rule out laboratory error. 1, 2
This patient's random blood sugar of 7.2 mmol/L does NOT meet the threshold for unequivocal hyperglycemia (which requires ≥11.1 mmol/L or ≥200 mg/dL with classic symptoms), so confirmation is absolutely required. 1
The Proper Diagnostic Approach
Repeat the fasting plasma glucose test on a subsequent day, ensuring the patient has fasted for at least 8 hours and the test is performed on venous plasma in a certified laboratory. 1, 2
If the repeat fasting glucose is ≥7.0 mmol/L (≥126 mg/dL), the diagnosis of diabetes is confirmed. 1, 2, 3
If the repeat value is 5.6-6.9 mmol/L (100-125 mg/dL), the patient has impaired fasting glucose (prediabetes). 1
Alternatively, you can use a different confirmatory test such as HbA1c (≥6.5% confirms diabetes) or a 2-hour oral glucose tolerance test (≥11.1 mmol/L confirms diabetes), and if both tests are above diagnostic thresholds, diabetes is confirmed without needing to repeat the original test. 1, 2
Why Starting Metformin Now is Premature (Option C is Wrong)
Do not start treatment based on a single glucose measurement unless the patient has unequivocal hyperglycemia with classic symptoms or hyperglycemic crisis. 1, 2
Laboratory errors and preanalytic variability occur frequently, making confirmation essential before committing a patient to lifelong diabetes treatment. 1, 2
While this patient has symptoms (fatigue and polydipsia), his random glucose of 7.2 mmol/L is far below the 11.1 mmol/L threshold required to diagnose diabetes on a single random measurement with symptoms. 1
Why "Tolerate Symptoms" is Dangerous (Option B is Wrong)
This patient has a strong family history of diabetes, symptoms suggestive of hyperglycemia, and an elevated glucose level that warrants immediate diagnostic evaluation. 1, 4
Delaying diagnosis allows potential progression of uncontrolled hyperglycemia and increases risk of complications. 4
Critical Pitfalls to Avoid
Do not rely on point-of-care glucometry alone for diagnosis—abnormal results must be confirmed with standardized laboratory testing on venous plasma. 3
Ensure proper fasting conditions (at least 8 hours, no caloric intake) when performing the confirmatory test. 1, 3
If the repeat test is borderline or discordant with the first result, the test whose result is above the diagnostic threshold should be repeated again, and diagnosis is made based on the confirmed test. 1