N: Number of participants; CT: Clinical trial; TTR: Transthyretin; IRR: Infusion-related reaction; RBP: Retinol-binding protein; RCT: Randomized controlled trial; mNIS: Modified neuropathy impairment score; QOL: Quality of life; QOL-DN: Quality of life diabetic neuropathy; ITT: Intention to treat; CFT: Cardiac function test; pBNP: Pro-brain natriuretic peptide. Here, RBP4 is linked to diabetic neuropathy.