Step 1: Understanding the symptoms.
The patient presents with classic symptoms of hyperglycemia, including unexplained weight loss, excessive thirst, and frequent urination. These are commonly seen in diabetes. The blood glucose level of 250 mg/dL is elevated but not as high as in conditions like diabetic ketoacidosis or hyperosmolar hyperglycemic state.
Step 2: Analyzing the options.
(1) Type 2 diabetes: This is the most likely diagnosis. The symptoms and blood glucose level fit well with Type 2 diabetes, which is more common in adults.
(2) Type 1 diabetes: Type 1 diabetes often presents with more severe symptoms, such as diabetic ketoacidosis, which is not mentioned in this case.
(3) Diabetic ketoacidosis: Diabetic ketoacidosis typically presents with a much higher blood glucose level and additional signs like fruity breath, vomiting, and dehydration.
(4) Hyperosmolar hyperglycemic state: This condition involves much higher blood glucose levels, often over 600 mg/dL, and would not fit the current clinical presentation.
Step 3: Conclusion.
The most likely diagnosis is (1) Type 2 diabetes, as the symptoms and glucose level are characteristic of this condition.