Background: Patients with diabetes and systemic lupus erythematosus (SLE) frequently have sleep disruption. Unfortunately, there is still a lack of knowledge about the relationship between the incidence of sleep disorders in SLE and the causes of these disorders. Objectives: To study the sleep breathing disorders among diabetic patients with systemic lupus erythematosus (SLE) and associated relationship with both disease severity and activity. Patients and Methods: Thirty diabetic patients with SLE and thirty apparent healthy control subjects were enrolled in this work. For all patients, full medical histories, in-depth clinical exams, Epworth sleepiness ratings (ESS), laboratory evaluations, and complete overnight polysomnography were done. Results:Diabetic patients with SLE have a lower significant total sleep time (TST), sleep onset, sleep efficiency (%), percent of sleep in supine than controls (p < 0.001 for all). However, diabetic patients with SLE have a higher significant Spon Arousal index, number of awaking/hour, low limitation index and apnea/hypopnea index in supine than controls (p < 0.001 for all). Diabetic patients with SLE have a higher significant periodic leg movements during sleep (PLMS) sequence, apnea/hypopnea index (AHI), oxygen desaturation events (OD), percent of snoring time in TST, percent of rapid eye movement sleep (REM) in TST, total AHI in non-rapid eye movement sleep (NREM), total AHI in REM, ESR, CRP, uric acid and FBS, HBA1c% than controls (p < 0.001 for all). However, diabetic patients with SLE have a lower significant average oxygen saturation % and lowest oxygen saturation (%) than controls (p < 0.001 for all). Conclusion: Sleep breathing problems are frequently seen in people with systemic lupus erythematosus and diabetes. These patients' disease activity and poor glycemic management may be significant contributors to their sleep disruption.