**Question:** A 42-year-old male has strong positive Benedict's test, random blood sugar is > 163 mg%, fasting blood sugar is > 200 mg%. Next line of investigation is -

A. Oral Glucose Tolerance Test (OGTT)
B. Serum Creatinine
C. Serum Uric Acid
D. Serum Bilirubin

**Correct Answer:**

**Core Concept:**

The Benedict's test is a qualitative method used to detect the presence of reducing sugars in a biological sample, such as urine or blood. A positive test result indicates the presence of glucose or other reducing sugars, which are indicative of impaired glucose tolerance or diabetes mellitus. Random blood sugar (RBS) and fasting blood sugar (FBS) are laboratory tests used to evaluate carbohydrate homeostasis in the body.

**Why the Correct Answer is Right:**

In the given scenario, the patient presents with a strong positive Benedict's test, elevated random blood sugar (RBS) of >163 mg%, and elevated fasting blood sugar (FBS) of >200 mg%. These findings are highly suggestive of impaired glucose tolerance or diabetes mellitus. The Oral Glucose Tolerance Test (OGTT) is the next appropriate step in the diagnostic algorithm, as it provides a comprehensive assessment of glucose homeostasis and helps differentiate between different types of diabetes mellitus.

**Why Each Wrong Option is Incorrect:**

**Option A (Serum Creatinine):** Serum creatinine is a renal function test that measures the clearance of creatinine from the body, which is unrelated to glucose homeostasis. Hence, this option is incorrect.

**Option B (Serum Bilirubin):** Serum bilirubin is a liver function test that assesses the liver's ability to conjugate bilirubin, which is unrelated to glucose homeostasis. This option is incorrect.

**Option C (Serum Uric Acid):** Serum uric acid is a kidney function test that assesses the ability of the kidneys to excrete uric acid, not related to glucose homeostasis. This option is incorrect.

**Option D (Serum Creatinine):** As explained above, serum creatinine is a renal function test, unrelated to glucose homeostasis. This option is incorrect as well.

**Clinical Pearls:**

1. A positive Benedict's test, elevated RBS, and FBS suggest impaired glucose tolerance or diabetes mellitus.
2. OGTT is essential to differentiate between impaired glucose tolerance and diabetes mellitus.
3. Renal function tests (Option A, B, C, and D) are unrelated to glucose homeostasis and do not contribute to the diagnosis of diabetes.
4. OGTT is the gold standard test for diagnosing diabetes mellitus.