High quality communication between health care providers (HCPs) and adolescents and young adults (AYAs) with type 1 diabetes (T1D) may contribute to better diabetes self-care and health outcomes. Health communication reflects both informational content and how information is conveyed, including affect and tone. The aim of this study was to assess HCP affective communication and the relationship between HCP affective communication and glycemic control in AYAs with T1D. As part of a larger study of AYA-HCP health communication, routine clinic visits for 69 AYAs with T1D (M age 17.81 years; 56.5% female) and 8 HCPs (88% female) were audiorecorded. Clinic visits were coded using the Roter Interaction Analysis System (RIAS), a validated coding structure assessing verbal and non-verbal exchanges in a medical encounter. HCP global affective ratings were used to create two composite variables—positive HCP affect (e.g., attentiveness; respectfulness; Cronbach’s a = 0.82) and negative HCP affect (e.g., anger; dominance; Cronbach’s a = 0.75). Hemoglobin A1c (A1c) was taken from the medical chart. The mean A1c was 8.97% (±2.30). Descriptive analyses of positive and negative HCP affect indicated that HCPs expressed a high level of positive affect (M = 4.21) and a relatively low level of negative affect (M = 2.80). Negative affect was positively associated with HbA1c. After controlling for salient covariates (e.g., HCP, race, regimen), A1c accounted for a significant portion of the variance in negative affect during the clinic visit (Adj R2 =.36, ß = 0.57, p < 0.001). This sample of HCPs predominantly exhibited positive affect during routine T1D visits. Glycemic control was not associated with positive affect, but higher A1c was associated with more negative affect. This finding suggests elevated A1c levels may elicit more negative affect in routine diabetes care. Future research should examine these associations over time, including how AYA-HCP health communication quality predicts long-term glycemic control. Disclosure K. Homma: None. F.R. Cogen: None. R. Streisand: None. M. Monaghan: Research Support; Self; American Diabetes Association, National Institutes of Health.