OBJECTIVES: Little evidence exists whether the presence of concordant comorbidity (CC) or discordant comorbidity (DC) further burden the patients with diabetes mellitus (DM). The purpose of this study was to evaluate and quantify the impact of types of comorbid conditions on healthcare expenditures in patients with DM.  METHODS: Using the 2011-2013 Medical Expenditure Panel Survey data, adult DM patients were identified. The twenty different chronic conditions were captured and three mutually exclusive groups were created; 1) DM only, 2) DM plus CC only, and 3) DM plus DC. Total healthcare expenditures included pharmacy, office visits, emergency department, inpatient, and residual costs. Generalized linear models with log rank and gamma distribution were used to estimate adjusted annual healthcare expenditures based on the type of comorbidity. Incremental costs and confidence intervals were estimated using a nonparametric cluster bootstrapping method. RESULTS: A sample of 8,604 adult DM patients was identified of which 11.4% had DM only, 40.5% had DM plus CC only, and 48.1% had DM plus DC. The most observed comorbidities were hypertension and dyslipidemia for CC, and depression and arthritis for DC. The economic burden was higher for the DM patients with DC as compared to those with CC only. The estimated average total annual expenditures were $4,792 (95% CI $4,152-$5,697) for DM only, $6,157 ($5,415-$7,012) for DM with one CC, and $9,344 ($6,452-$12,845) for DM with one DC. The incremental health expenditures of the DM plus DC relative to the DM plus CC were $3,186 ($32-$6,821), $3,738 ($200-$3,142), and $1,050 ($-1,786-$3,888) for patients with one, two, and three or more comorbidities, respectively. The higher expenditures were mainly driven by higher office visit costs and pharmacy costs.   CONCLUSIONS: Higher economic burden in DM patients was associated with DC than CC. Future intervention strategies should focus on DM patients with unrelated comorbidities to lower the financial burden.