Introduction: Obesity and type 2 diabetes mellitus have reached epidemic proportions worldwide. Abnormal sleep has been linked to both incident and prevalent obesity and type 2 diabetes. We aimed to characterize abnormal sleep patterns [ASP’s] in patients with obesity, type 2 diabetes, or both.Subjects: The study included 92 subjects divided into four groups: Group 1, 23 obese patients (BMI > 30) with type 2 diabetes mellitus; Group 2, 23 non-obese diabetic patients; group 3, 23 obese subjects without diabetes; group 4, 23 matched healthy control subjects.Methods: Waist circumference and BMI [body mass index] estimation, fasting and post challenge plasma glucose ‘‘groups 2 & 4”, HOMAIR [Homeostatic model assessment- Insulin resistance] estimation, and finally evaluation for ASP’s using a CDC [Centers for Disease Control and prevention] validated questionnaire.Results: Post-prandial glucose and BMI significantly predicted Sleep latency and sleep hours at night respectively. Both group 1 and 3 compared to group 4 showed higher prevalence of: Insomnia [p < .01], snoring [p < .01], fragmented sleep [p < .05], excessive day time sleepiness [p < .001], and daytime dysfunction [p < .001]. Group 2 compared to group 4 showed higher prevalence of: Insomnia, snoring, fragmented sleep, and finally, daytime dysfunction [All p < .01]. Group 1 compared to groups 3 and 4 had significantly less hours of sleep at night [p < .01]. Group 1 compared to group 2 showed higher prevalence of: Insomnia, fragmented sleep, excessive day time sleepiness, and daytime dysfunction [All p < .05]. Finally, group 3 compared to group 2 showed higher prevalence of: Excessive day time sleepiness, and daytime dysfunction [p < .01].Conclusion: The combination of obesity and diabetes mellitus is associated with poor quality and quantity of sleep with resultant significant daytime dysfunction. Glycemic, and adiposity measures predicted sleep latency and hours.Keywords: Type 2 diabetes, Obesity, Abnormal sleep patterns, Insulin resistance Latency period, Impaired daily activitie