Benedryl or namely Diphenhydramine(the chemical name) can give you a feeling of euphoria. It is not safe to take in large amounts and should not be used in this manner. but if you are going to BE VERY CAREFUL! 25-50 mgs is the normal dose. if you take more than that you could go into respiratory or cardiac arrest.
Insulin deficiency (symptom description): For a medical symptom description of 'Insulin deficiency', the following symptom information may be relevant to the symptoms: Diabetes-like symptoms (type of symptom). However, note that other causes of the symptom 'Insulin deficiency' may be possible.
When insulin loses potency, blood glucose levels will rise and become inconsistent. Often the insulin will still work somewhat - just not as well. It can cause confusion when trying to determine what part of your diabetes plan is not working. It can contribute to days or weeks of high blood glucose levels.