Sikhs have great respect for life, which is regarded as a gift from Waheguru [Waheguru: A Punjabi term used in Sikhism to refer to God. ]. Therefore most Sikhs are opposed to euthanasia [Euthanasia: Literally, 'good death'. ] as they believe that birth and death should be left in the hands of Waheguru.
God sends us and we take birth. God calls us back and we die.
Guru Granth Sahib 1239
The Sikh Gurus did not approve of suicide [Suicide: Intentionally taking one's own life. ] as it interferes with the plans of Waheguru.
They believed that suffering was the result of bad Karma[an error occurred while processing this directive] and that people should accept it without complaint but try to make the best of the situation. Sikhs believe that life is given by Waheguru and although it may be joyful or sorrowful, long or short, no one but Waheguru has the right to shorten it
Death is seen as a gateway into another life:
The dawn of a new day is the herald of a sunset. Earth is not your permanent home.
Guru Granth Sahib 793
The Sikh teaching about Sewa[an error occurred while processing this directive] and caring for others suggests that the correct response to situations would be to provide such good care that euthanasia became an unattractive option.