Dual Eligible Special Needs Plans (D-SNPs) enroll beneficiaries who are entitled to both Medicare (Title XVIII) and Medical Assistance from a State Plan under Title XIX (Medicaid), and offer the opportunity of enhanced benefits by combining those available through Medicare and Medicaid.
Further reading –
https://www.cms.gov/Medicare/Health-Plans/SpecialNeedsPlans/DualEligibleSNP.html#s1