Biessels GJ, Janssen J, van den Berg E, Zinman B, Espeland MA, Mattheus M, Johansen OE. Rationale and design of the CAROLINA® - cognition substudy: a randomised controlled trial on cognitive outcomes of linagliptin versus glimepiride in patients with type 2 diabetes mellitus. BMC Neurol. 2018 Jan 15; 18(1):7.