What is the next step in managing a patient with a family history of diabetes, presenting with fatigue, polydipsia, and a random blood sugar of 7.2 mmol/L?

Next Step: Confirm the Diagnosis with Proper Testing

The first next step is to repeat the random blood sugar test with a fasting plasma glucose (FPG) or HbA1c to confirm whether this patient has diabetes or prediabetes (Option A). 1

Why Confirmatory Testing is Essential

This patient presents with classic symptoms of hyperglycemia (fatigue and polydipsia) and has a random blood sugar of 7.2 mmol/L (approximately 130 mg/dL). However, this value falls below the diagnostic threshold for diabetes.

Understanding the Diagnostic Criteria

• For diabetes diagnosis using random plasma glucose: The threshold is ≥200 mg/dL (11.1 mmol/L) when classic symptoms are present 1
• This patient's value of 7.2 mmol/L (130 mg/dL) is below the diagnostic threshold but is abnormal and warrants further investigation 1, 2
• In the absence of unequivocal hyperglycemia (≥200 mg/dL), diagnosis requires confirmatory testing with either a repeat test or an alternative diagnostic method 1

Recommended Confirmatory Tests

Order one of the following tests to establish the diagnosis: 1, 2

• Fasting Plasma Glucose (FPG): ≥126 mg/dL (7.0 mmol/L) confirms diabetes; 100-125 mg/dL (5.6-6.9 mmol/L) indicates impaired fasting glucose (prediabetes) 1, 2
• HbA1c: ≥6.5% confirms diabetes; 5.7-6.4% indicates prediabetes 1, 2
• 2-hour oral glucose tolerance test (OGTT): ≥200 mg/dL (11.1 mmol/L) confirms diabetes; 140-199 mg/dL (7.8-11.0 mmol/L) indicates impaired glucose tolerance 1, 2

The FPG or HbA1c are preferred over OGTT due to greater convenience and practicality. 1

Why Not Start Metformin Now (Option C is Wrong)

Starting metformin without confirming the diagnosis is premature and inappropriate. 1

• The diagnosis of diabetes has not been established—the random glucose of 7.2 mmol/L does not meet diagnostic criteria 1
• Treatment decisions depend on whether the patient has diabetes, prediabetes, or normal glucose metabolism 2, 3
• If the patient has prediabetes rather than diabetes, lifestyle modifications (5-7% weight loss and 150 minutes/week of moderate physical activity) are first-line interventions, with metformin considered as adjunctive therapy 3

Why Not Dismiss the Symptoms (Option B is Wrong)

Telling the patient to tolerate symptoms and return if they worsen is dangerous and neglectful. 1, 4

• The patient has classic symptoms of hyperglycemia (fatigue and polydipsia) combined with an elevated random glucose 1
• He has a strong family history (mother with diabetes), which significantly increases his risk 2, 3, 4
• Early diagnosis and intervention prevent progression to diabetes and reduce long-term complications including blindness, limb amputation, kidney failure, and cardiovascular disease 4
• Delaying diagnosis allows potential progression from prediabetes to diabetes, missing the critical window for effective lifestyle intervention 3, 4

Clinical Approach Algorithm

Follow this stepwise approach: 1

1. Order confirmatory testing immediately: FPG (preferred for convenience) or HbA1c 1, 2
2. If FPG ≥126 mg/dL or HbA1c ≥6.5%: Repeat the same test on a different day to confirm diabetes diagnosis 1
3. If both tests are above diagnostic thresholds: Diabetes is confirmed without need for additional testing 1
4. If results show prediabetes (FPG 100-125 mg/dL or HbA1c 5.7-6.4%): Initiate intensive lifestyle modifications and consider metformin 2, 3
5. If diabetes is confirmed: Begin comprehensive diabetes management including lifestyle modifications, metformin as first-line pharmacotherapy, and monitoring for complications 2, 4

Important Caveats

• The random glucose of 7.2 mmol/L, while not diagnostic, is concerning in the context of symptoms and family history and should never be ignored 2, 4, 5
• Ensure the confirmatory test is performed in an accredited laboratory using venous plasma, not point-of-care glucometry, for diagnostic accuracy 6, 2
• The patient should fast for at least 8 hours before FPG testing to ensure valid results 1, 6
• If HbA1c is used, ensure the laboratory uses an NGSP-certified method standardized to the DCCT assay 1, 2