As I've mentioned previously acupuncture is not a point - to - condition modality. In other words you do not simply match points with conditions and treat a person. Chinese Medicine generally uses patterns to treat conditions which means while there are some empirical points for various conditions the treatments are ultimately tailored to each individual. To properly design a treatment involves years of proper training. For diabetes I would start in our conditions treated section (click on "conditions" at the top bar) by reading the Type II Diabetes options page. Within you will find articles, herbal formulas and near the bottom of the page acupuncture protocols, tcm theory related to diabetes, and tam healing system (our system) protocols (which can be applied with massage, acupuncture, and/or tong ren therapy). While many of the protocols are intended for practitioners, a layperson such as yourself can still learn how we view these conditions and the patterns involved with them. Furthermore the tam healing system points can be used with self-massage (or with help from someone) and with tong ren therapy (a form of energy healing) without modification.
To specifically answer your question there isn't a single auricular point for type II diabetes. Along that note, in my opinion, auricular acupuncture alone is not enough to treat a complex condition such as diabetes. Personally, I would find a fully trained acupuncturist who uses body points along with herbal medicine. As far as duration of treatment - diabetes is a fairly serious condition that requires both proper treatment and generally lifestyle/diet change by the patient. It is not uncommon for treatment to span from 3 months to longer depending on the individual case.