A change to 100-unit insulin dosage will reduce errors.

Patients with diabetes were first treated with insulin in 1922. Insulin was then prepared at a concentration of 20 units/ ml, but later insulin strengths of 40 and 80 units/ml were introduced to reduce the injected volume. For patients needing very large doses, strengths of 320 and 500 units/ml have also been manufactured. The original insulin syringe was designed with 20 divisions (marks) per ml for use with 20 units/ml insulin. Though many new syringes were made in gradations to match U40 and U80 insulins in the United Kingdom, the syringe with 20 marks/ml bearing the British Standard Number BS1619 became the standard. This syringe is recommended for all diabetic patients in the UK, and it is specified in the Drug Tariff as an approved appliance that can be prescribed by general practitioners under the Family Practitioner Services of the National Health Service. This has led to the need to calculate and prescribe unit doses in terms of syringe divisions with 2 units/"mark" for U40 and 4 units/"mark" for U80. Not surprisingly, many errors are made in insulin dosage-not only by patients but also by doctors and nurses unfamiliar with the system. Many have even now failed to grasp the system of marks and units. Errors in dosage ranging between four times and one-quarter the intended unit dose are being given. Hypoglycaemia or ketoacidosis may result, sometimes with serious sequelae. Investigation The British Diabetic Association asked the doctors in its Medical and Scientific Section to record on a questionnaire their recent experiences of clinical problems-hazards and misadventures arising directly out of the confusion over the various strengths of insulin that are available. The inquiry was not intended to estimate the frequency of such misadventures, which would be much more complex and time consuming, but was made simply to illustrate (with details of cases given confidentially) the existence of problems and the form that they might take. Eighty-five replies were received in 10 weeks. The names of consultants, hospitals, and patients are confidential. Fifty-five replies specified instances of dosage errors arising from the confusion between the strengths of 40 and 80 units/ml of insulin. Twenty-six replies confirmed that the consequences