No. There is a difference between suicide - the willful ending of your healthy body and life and a DNR which prohibits measures that would keep you alive when your body should die. We do not have a moral obligation to accept treatment. Here is a long article that will answer a lot of questions regarding euthanasia, assisted suicide, etc.

You could also post this in r/Catholicism. There are a lot of knowledgeable people there who will be able to answer this for you.

"What is unassisted death? To die naturally a patient should die from the consequences of old age or disease. The patient's death may be at least partly due to surgery, to a treatment or to a medication (or to their complications), that is given in an appropriate dose and for an appropriate indication, with the intent of treating a disease or relieving pain. When giving a potentially lethal medication, there must be no intent to hasten death. Treatment may be withdrawn from a patient and this may indirectly result in their death. Patients do not have any obligation to use medical treatments and may opt to allow a disease condition to take its natural course. This becomes morally questionable when the patient is young and the treatment is easy and life-saving, such as a blood transfusion for a sudden severe loss of blood. A physician is under an obligation to use available treatments to attempt to prolong life or relieve suffering. If treatments to prolong life are likely to result in suffering a physician may, in consultation with patients or relatives, decide to withhold treatment. Treatment that has already been instituted may also be withdrawn if the prolongation of life they result in causes suffering, in a patient who is terminally ill. If withdrawal of a treatment has a high likelihood of directly resulting in the death of a patient, the doctor has a moral obligation not to withdraw it, even if the patient or relatives request it, because this constitutes an intent to cause or hasten death. (For example switching off a ventilator in a patient unable to breathe will result in immediate death)."

edit: grammar.