Travelling with Diabetes medication that is not for me

Are you having a stopover at Dubai? There is some information here if you are. It is information for U.S citizens but feel sure that it would apply to all.

http://www.saudiembassy.net/services/Bringing_Prescription_Drugs_into_the_Kingdom.aspx

If the prescription drug is in the possession of someone other than the patient (spouse, parents, children, or siblings) a copy of that person’s identification must be submitted with the clearance application. However, if that person is not a relative he/she must submit a document showing patient’s consent or authorization for him/her to handle the patient’s medications along with a copy of his/her identification.

I do not know about SriLanka but will bump your post up for replies.
You could contact the Sri Lanka embassy,
http://www.srilankahighcommission.co.uk/index.php?option=com_content&view=article&id=84&Itemid=92

You could also contact
https://www.diabetes.org.uk as they may be able to help.

You should get documents, I always travel with them, but.
I'm a Type 1 diabetic and have traveled with insulin for over 30 years, the few times I have been questioned it has always been the needles they have found (after 9/11 some airports do notice some times), they never bother when they see or I tell them that it is for Insulin. I have never shown any documentation that I'm a diabetic.