This study examined differences in diet quality by meal type, location, and time of week in youth with type 1 diabetes mellitus. A sample of youth with type 1 diabetes mellitus (n=252; 48% female) age 8 to 18 years (mean±standard deviation=13.2±2.8 years) with diabetes duration ≥1 year (mean±standard deviation=6.3±3.4 years) completed 3-day diet records. Multilevel linear regression models tested for differences in diet quality indicators by meal type, location, and time of week (weekdays vs weekends). Participants showed greater energy intake and poorer diet quality on weekends relative to weekdays, with lower intake of fruit and vegetables, and higher intake of total and saturated fat. Differences in diet quality were seen across meal types, with higher nutrient density at breakfast and dinner than at lunch and snacks. Participants reported the highest whole-grain and lowest fat intake at breakfast, but higher added sugar than at lunch or dinner. Dinner was characterized by the highest fruit intake, lowest added sugar, and lowest glycemic load, but also the highest sodium intake. The poorest nutrient density and highest added sugar occurred during snacks. Diet quality was poorer for meals consumed away from home than those consumed at home for breakfast, dinner, and snacks. Findings regarding lunch meal location were mixed, with higher nutrient density, lower glycemic load, and less added sugar at home lunches, and lower total fat, saturated fat, and sodium at lunches away from home. Findings indicate impacts of meal type, location, and time of week on diet quality, suggesting targets for nutrition education and behavioral interventions.