BACKGROUND: Early hypertension control reduces the risk of cardiovascular complications among patients with diabetes mellitus. There is a need to improve hypertension management among patients with diabetes mellitus. OBJECTIVE: We aimed to evaluate rates and associations of hypertension diagnosis and treatment among patients with diabetes mellitus and incident hypertension. DESIGN: This was a 4-year retrospective analysis of electronic health records. PARTICIPANTS: Adults ≥18 years old (n=771) with diabetes mellitus, who met criteria for incident hypertension and received primary care at a large, Midwestern academic group practice from 2008 to 2011 were included MAIN MEASURES: Cut-points of 130/80 and 140/ 90 mmHg were used to identify incident cases of hypertension. Kaplan-Meier analysis estimated the probability of receiving: 1) an initial hypertension diagnosis and 2) antihypertensive medication at specific time points. Cox proportional-hazard frailty models (HR; 95 % CI) were fit to identify associations of time to hypertension diagnosis and treatment. KEY RESULTS: Among patients with diabetes mellitus who met clinical criteria for hypertension, 41 % received a diagnosis and 37 % received medication using the 130/ 80 mmHg cut-point. At the 140/90 mmHg cut-point, 52 % received a diagnosis and 49 % received medication. Atrial fibrillation (HR 2.18; 1.21-4.67) was associated with faster diagnosis rates; peripheral vascular disease (HR 0.18; 0.04-0.74) and fewer primary care visits (HR 0.93; 0.88-0.98) were associated with slower diagnosis rates. Atrial fibrillation (HR 3.07; 1.39-6.74) and ischemic heart disease/congestive heart failure (HR 2.16; 1.24-3.76) were associated with faster treatment rates; peripheral vascular disease (HR 0.16;) and fewer visits (HR 0.93;) predicted slower medication initiation. Diagnosis and treatment of incident hypertension were similar using cut-points of 130/80 and 140/90 mmHg. CONCLUSIONS: Among patients with diabetes mellitus, even using a cut-point of 140/90 mmHg, approximately 50 % remained undiagnosed and untreated for hypertension. Future interventions should target patients with multiple comorbidities to improve hypertension and diabetes clinical care.