**Question:** Which of the following is the most probable diagnosis in a 35 years old man whose fasting and his post prandial blood sugar are within normal limits but urine sugar is three plus (+++)?

A. Diabetes mellitus
B. Acidosis
C. Hyperglycemic crisis
D. Hyperglycemic hyperosmolar state

**Correct Answer:** D. Hyperglycemic hyperosmolar state

**Core Concept:** Diabetes mellitus is a group of diseases characterized by high blood sugar levels due to insulin deficiency or insulin resistance. Hyperglycemic hyperosmolar state (HHS) is a severe form of diabetes mellitus often seen in patients with type 2 diabetes, characterized by hyperglycemia, hyperosmolarity, and often confusion or coma.

**Why the Correct Answer is Right:** In this case, the patient's fasting and postprandial blood sugar are within normal limits, ruling out diabetes mellitus and hyperglycemic hyperosmolar state (option D).

The patient's urine sugar is three plus (+++), which is a clinical sign of excessive glucose excretion due to hyperglycemia. This requires a diagnosis that is not limited to hyperglycemia, but also encompasses hyperosmolarity.

**Why Each Wrong Option is Incorrect:**

**A. Diabetes mellitus:** While this condition may present with hyperglycemia, it typically does not have hyperosmolarity and may be accompanied by ketonuria.

**B. Acidosis:** Acidosis is a condition characterized by an abnormal increase in blood acidity, which is not the main feature in this case.

**C. Hyperglycemic crisis:** This term refers to a severe hyperglycemic episode, but it does not specifically account for the hyperosmolar component mentioned in the clinical scenario.

**Clinical Pearl:** A thorough evaluation of a patient presenting with hyperglycemia and hyperosmolarity is essential to identify the appropriate diagnosis. Hyperglycemic hyperosmolar state should be considered when a patient has severe hyperglycemia and hyperosmolarity without acidosis or ketonuria, especially in the context of type 2 diabetes mellitus.