請問糖尿藥可否入境英國，它是否受藥物管制名單下？

任何藥物最好把醫囑處方單或診斷書帶著， 醫院給的藥袋直接帶著， 有你姓名， 劑量， 服用方法。

英國海關官網，你直接查你的藥有沒有在其中或其成份。
Travelling with medicine containing a controlled drug
You need to prove your medicine is prescribed to you if:
https://tw.answers.yahoo.com/question/index?qid=20190214032247AAvr3J8

it contains a ‘controlled drug’
you have it on you when you’re entering or leaving the UK
You may also need to get a licence.

英國海關管制藥品清單
https://www.gov.uk/government/publications/controlled-drugs-list--2/list-of-most-commonly-encountered-drugs-currently-controlled-under-the-misuse-of-drugs-legislation

Yes and no.

1. The actual formula matters.

2. Controlled or not - the rule of thumb for bringing medicine is unless you can purchase the medicine in a retail environment without prescription, only the person which the medicine is prescribed can bring the medicine into a country.