PURPOSE: Antihyperglycemic medication intensification practices among patients with incident diabetes are incompletely understood. We characterized the first intensification the year after oral antihyperglycemic medication initiation among incident diabetes patients. METHODS: This retrospective cohort study across 11 US health systems included adults identified with incident diabetes between 2005 and 2009 who started oral antihyperglycemic monotherapy or combination therapy within 6 months after diabetes identification. We determined intensification, defined as increased index medication dosage, addition of another oral medication, or switch to/addition of insulin 31-365 days after initial antihyperglycemic dispensing. Cox regression was used to assess intensification for patient, temporal, and system covariates, adjusting for glycosylated hemoglobin (HbA1c) as a time-dependent variable. RESULTS: Among 41 233 patients, 33.5% and 45.3% had treatment intensified within 6 and 12 months, respectively. This first intensification was most often with increased index medication dosage (78%), least often with insulin (<1%). HbA1c% was strongly associated with intensification (adjusted hazard ratios [HR] 1.59, 3.62, 4.44, and 5.52 for HbA1c 6.5% to <7%, 7% to <7.5%, 7.5 to <8%, and >/=8%, respectively, all P < 0.001, compared with HbA1c < 6.5%). In patients initially on monotherapy, age modified the HbA1c effect: at HbA1c < 7%, the HR differed little between middle-aged and older patients; at HbA1c >/= 7%, the HR decreased with older age (e.g., age 40-49 years and HbA1c >/= 8%: HR 8.14; age >/= 80 years and HbA1c >/= 8%: HR 4.44; compared with age >/= 80 years and HbA1c < 6.5%). Within 1 year, 84.3% achieved HbA1c < 8%; 65.1% achieved HbA1c < 7%. CONCLUSIONS: Clinicians appear to be applying treatment intensification guidelines and individualizing therapy by considering patient age, achieving glycemic control among most incident diabetes patients.