OBJECTIVE - To explore associations between diabetes etiology (type 1 diabetes mellitus [T1DM] vs. T2DM) and glycemic control in the prediction of 5-year periodontal status change. RESEARCH DESIGN AND METHODS - The Study of Health in Pomerania (SHIP) is a population-based stratified sample of German men and women. Healthy participants and those determined to have T2DM arose fromthe SHIP cohort, and T1DM participants were recruited from diabetes clinics in the catchment area that gave rise to SHIP. Dentate participants (n = 2,626; 53% women; 20-81 years of age)were included. Diabetes was determined via physician diagnosis and/or HbA1c ≥6.5% (uncontrolled diabetes ≥7.0%). Examiners blinded to diabetes status performed random half-mouth periodontal examinations, assessing probing depth (PD) and attachment loss (AL) (four sites/tooth) at baseline and follow-up. Participants were categorized into six groups as follows: 1) diabetes free (n = 2,280), 2) incident T2DM (n = 79), 3) controlled T2DM (n = 80), 4) uncontrolled T2DM (n = 72), 5) controlled T1DM (n = 43), and 6) uncontrolled T1DM (n = 72). Inmultivariable regressions,mean PDchange (ΔMPD),mean AL change (ΔMAL), or incident toothloss values were regressed across the aforementioned diabetes categories. RESULTS - Mean (SD)ΔMPD and ΔMAL values among all participants were -0.08 ± 0.5mm and 0.08 ± 1.03 mm, respectively, and 34% lost one or more teeth. Relative to diabetes-free participants, thosewith uncontrolled T2DM experienced greater ΔMPD ± SE (P<0.05), whereas participantswith either uncontrolled T1DM or uncontrolled T2DM realized greater ΔMAL (P<0.05). Uncontrolled T1DM and T2DM were both associated with an increased risk of future tooth loss (P<0.05). CONCLUSIONS - Diabetes control, but not etiology, was associated with future tooth loss and accelerated AL progression.