The term 'human insulin' is a misnomer, as its source is not human pancreas but the pork pancreas from where insulin is humanised by modern techniques of genetic engineering. With the use of purified animal insulin, untoward effects occur infrequently. Porcine insulin is different from human insulin in only one amino acid. They have also been found to be equal in terms of effect on plasma glucose, glycated haemoglobin and insulin dose requirements. A lesser written fact is that while human insulin can produce all the problems encountered with animal insulin, there are certain more serious additional problems experienced with use of human insulin.