Collecting a urine sample for C-Peptide / Creatinine ratio

This test is to check whether or not your body is naturally producing any insulin. 

Collect the sample Monday or Tuesday after breakfast or lunch. Wednesday after breakfast. It needs to be dropped at the surgery on the same day, before 3pm.


  1. Empty your bladder into the toilet.
  2. Take your insulin with your meal as you normally would.
  3. Eat your breakfast or lunch (ensure your meal contains carbohydrate - a starchy food like bread or cereal).
  4. After, do not eat or drink anything apart from water for 2 hours until you have taken the urine sample. However if you feel your blood sugar is low you will need to treat this and do the test another day.
  5. Approximately 2 hours after this meal, empty your bladder again and collect a sample of this urine as detailed below.

Do not take this sample whilst you are menstruating.

To collect your urine sample

  1. Pass your urine into the plastic pot and transfer to the white top specimen tube (or use a green container if provided with this already).
  2. Write your full name, date of birth, hospital or NHS number and the time and date of the collection on the tube.
  3. Place the specimen tube and request form into the bag provided.

After you have collected the sample

  1. Bring the sample to the Burdwood Surgery as soon as it has been collected, this needs to be before 3pm.
  2. Place the sample in the sample box which is located by the toilets near reception.

If you need help with this, please contact us online