OBJECTIVES: To assess clinical outcomes among individuals having chronic illness with complexity (CIC) defined as co-occurring type 2 diabetes mellitus (T2DM) and Parkinson’s disease (PD).  METHODS: This study used a retrospective cohort design using Humana Medicare Advantage Part D claims database (2007-2011) and included elderly (age ≥ 65 years) Medicare beneficiaries with T2DM (identified by ICD-9-CM code of 250.x0 or 250.x2). PD was identified using ICD-9-CM code of 332.xx. Individuals with T2DM and PD (CIC) were matched to those with T2DM and no PD (no CIC) on sex, age, and diabetes complications severity index based on 8 to 1 GREEDY matching algorithm using propensity score. After propensity score matching there were 2,703 individuals with T2DM and PD and 8,109 with T2DM and no PD. Glycemic control outcomes [(i) < 8%, (ii) ≥ 8%, (iii) no HbA1c values] and lipid control outcomes [based on Low Density Lipoprotein Cholesterol (LDL-C) categorized into (i) <100 mg/dl, (ii) ≥ 100mg/dl, (iii) no LDL-C values] were measured during the year subsequent to the identification of T2DM and PD. Multinomial conditional logistic regressions were conducted to examine the association between PD and clinical outcomes.   RESULTS: Among those with laboratory values, 86.1% individuals with PD and 83.8% individuals without PD had <8% HbA1c value; the corresponding figures for LDL-C value of <100mg/dl were 75.5% and 69.8% respectively. Multinomial conditional logistic regressions revealed that individuals with PD were more likely than those without PD to have good glycemic control of <8% HbA1c (reference group: ≥ 8% HbA1c) (AOR: 1.34, 95%CI: 1.10-1.63) and good LDL-C control of <100mg/dl (reference group: ≥ 100mg/dl LDL-C) (AOR: 1.29, 95%CI: 1.03-1.63).  CONCLUSIONS: Individuals with CIC were more likely to have clinically recommended glycemic and LDL-C control compared to those without CIC, suggesting that integrated systems may be beneficial to those with CIC.