A 67 year old male presents with polyuria and nocturia. His BMI=33, urine culture = negative for nitrates. What is the next diagnostic investigation?

The key is E. Blood sugar. [Age at presentation and class1 obesity favours the diagnosis of type2 DM. Criteria for diagnosing diabetes mellitus are:

• a random venous plasma glucose concentration ≥ 11.1 mmol/l or

• a fasting plasma glucose concentration ≥ 7.0 mmol/l (whole blood ≥ 6.1 mmol/l) or

• two hour plasma glucose concentration ≥ 11.1 mmol/l two hours after 75g anhydrous glucose in

an oral glucose tolerance test (OGTT).

• An HbA1c of 48mmol/mol (6.5%) or more].