Methods are disclosed of treating diabetes, abnormal adipocyte activity, and insulin resistance using C-terminal fragments of adiponectin receptor R1. Methods of causing the secretion of insulin in healthy and diabetic patients using C-terminal fragments of adiponectin receptor R1 are also disclosed. In addition, methods are disclosed of increasing the insulin levels in healthy patients using C-terminal fragments of adiponectin receptor R1. In addition, methods of treating abnormal adipocyte activity, treating metabolic syndrome, causing insulin secretion, increasing insulin levels, inhibiting insulin degradation enzyme, treating Alzheimer's disease, treating cardiovascular disease associated with adiponectin levels, inhibiting ADAM-17 enzyme, treating a condition associated with TNF-alpha, and treating a condition associated with HER2-neu are disclosed. Compositions, dosage forms, and kits are also disclosed.