The treatment must be lifelong insulin replacement. Insulin treatment may be difficult to use. Insulin must be injected, and the dose must be closely adjusted to avoid high or low blood sugars in the presence of varying levels of physical activity, food intake and the physical state of the person taking the insulin. Since Banting’s and Best’s discovery of insulin, there have been major changes in the production and manufacture of insulin to improve the consistency and quality of insulin products. We have now moved away from animal derived insulin and most insulin currently sold is genetically engineered from bacteria. The insulin that is then produced is either stabilised without retardant, soluble insulin (Actrapid or Humulin S) or is crystallised or retarded with other agents (Ultratard, Humulin I and Insulatard). A small amount of animal derived insulin is still used by patients who have been stabilised on it, and in whom there is no clinical indication to switch to human insulin.

Insulin is given by injection, and this has been improved with development of the pen syringes. These devices still require an injection, but are more convenient to carry and speed up insulin administration. They enable multiple insulin injections throughout the day, and can be filled with a variety of types of insulin mixes to match the individual requirements. The new class of analogue insulin represents an exciting development in insulin therapy. These are genetically engineered insulins, in which the amino acids are altered to different sites to alter the physical characteristics and actions of insulin. Currently two products, Lispro insulin (Humalog)and Insulin Aspart (Novorapid) are available.

These insulins are more rapidly acting than conventional human insulin, and enable the person with diabetes to have less fluctuation in blood glucose after meals, to have fewer episodes of hypoglycaemia and reduced weight gain with improved overall glycaemic control when compared with soluble insulin. A further analogue insulin, Insulin Glargine (Lantus), has been recently released. This insulin has a “flatter” action profile, with a markedly prolonged length of action. This profile offers the possibility of improved basal action, with less nocturnal hypoglycaemia and lower fasting blood glucose concentrations. The combination of this analogue with one of the shorter acting analogues looks very promising in the search for an insulin regime that supports normal post-meal excursions of glucose concentrations without fasting hypoglycaemia. Recently, a further new insulin, Detimir, has been release which seems very predictable in it's action, with a typical duration of about 14-16 hours
However, even with these improvements, insulin treatment will continue to be difficult until we have automatic and self-governing insulin administration devices, or grafts of genetically manipulated insulin secreting cells.