Which test is used to confirm the diagnosis of diabetes mellitus?

The appropriate tests to confirm the diagnosis of diabetes mellitus include fasting plasma glucose and HbA1c. Fasting plasma glucose is used to determine the blood sugar level after a period of fasting and can indicate whether a person has diabetes based on specific cutoffs. The HbA1c test reflects average blood glucose levels over the previous two to three months and provides a convenient way to assess long-term glucose control.

Both of these tests are widely accepted and reliable for confirming diabetes. They are endorsed by health organizations such as the American Diabetes Association. In contrast, random plasma glucose and oral glucose tolerance tests can also be used for diagnosing diabetes, but they are generally considered supplementary or used in specific situations. Urine glucose tests are not a reliable standalone method for diagnosing diabetes as they can give false positive or negative results depending on various factors.

Thus, the combination of fasting plasma glucose and HbA1c stands out as the most definitive method for confirming the diagnosis of diabetes.