INS and type 2 diabetes mellitus: We assume that an increased insulin level in type II diabetes exerts an inhibitory effect on the pineal gland and melatonin, so a functional antagonism between insulin and melatonin has to be suggested.27 Complementary observations on type II diabetic patients displayed decreased melatonin plasma levels along with raised plasma insulin levels or increased pancreatic MT1- and MT2-receptor expression.28 The classic membrane associated melatonin receptors, in MT1 and MT2 mammals, have been found to be present in the pancreas and the islets of Langerhans.