The patient has diabetes.

You explain to Monica that the orange-red precipitate indicates that the urine sample contains glucose and that this surely means that the patient has diabetes. You remember that glucose should not normally be present in urine. 

Monica agrees with you that the test is indeed positive for glucose. Monica explains that Fehling's test is based on the reduction of copper(II) ions (Cu²⁺) to copper(I) ions (Cu⁺) by reducing sugars under alkaline conditions. This gives the solution an orange-red precipitate. 

Monica goes on to add that the test seems to have worked fine since it did not yield a positive result for sucrose, a non-reducing sugar.

[Sucrose must be broken down into its constituent monosaccharide units before Fehling’s test can be carried out. If sucrose is boiled with diluted hydrochloric acid, it will be hydrolyzed to glucose and fructose. It will then give a positive Fehling’s test.]

However, Monica is not entirely sure that a positive Fehling’s test is a definite diagnostic test for diabetes. You agree that you’d better check before presenting the results to Dr. Brown. A quick bibliographic search reveals that while glucose in the urine can indicate diabetes, there could also be other explanations for the presence of glucose, including medication and kidney disease. Therefore, further tests would need to be carried out for a definitive diagnosis. 

You and Monica are satisfied that you have carried out the test properly and can now present the results to Dr. Brown.