C-peptide occurs in

C-peptideA biologically inactive residue of insulin formation in the beta cells of the pancreas. When proinsulin is conveed to insulin, an equal amount of C peptide, a chain of amino acids, is also secreted into the bloodstream. Beta cell secretory function can be determined by measuring the C peptide in a blood sample.Proinsulin is a precursor of insulin, having low biologic activity.Glucagon is a polypeptide hormone secreted by the alpha cells of the islets of Langerhans in response to hypoglycemia or to stimulation by growth hormone.Thyroxine is a thyroid hormone that contains iodine and is a derivative of the amino acid tyrosine, occurring naturally as l-thyroxine; its chemical name is tetraiodothyronine.Ref: Ganong&;s review of medical physiology; 24th edition; page no-433