This study will be conducted to examine the effect of bitter orange oil inhalation aromatherapy on sleep quality and fatigue levels in patients with Type 2 Diabetes Mellitus (DM). The study will be conducted in the Endocrinology clinic of a university hospital in Türkiye. The research sample will consist of 100 adult patients. Patients will be randomly divided into two groups: the intervention and control groups. Patients in the intervention group will have three drops of bitter orange oil placed on a small cotton ball each night close to bedtime for three consecutive days. They will then hold the cotton ball 5 cm away from their nose and inhale it for one minute while breathing normally. After three consecutive nights of this procedure, sleep quality and fatigue levels will be measured on the morning of the fourth day. Patients in the control group will undergo the same procedure, but instead of orange oil, they will inhale water into the cotton ball.