BMA Concise Guide to Medicine & Drugs


Brand names Apidra, Humalog, Human Actrapid, Human Insulatard, Human Mixtard, Humulin, Hypurin, Insuman, Lantus, Levemir, NovoRapid, Pork Insulatard, Pork Mixtard, and others


Drug group Drug for diabetes

Overdose danger rating High

Dependence rating Low

Prescription needed Yes

Available as generic No


Insulin is a hormone made by the pancreas and vital to the body’s ability to use sugar. It is given by injection to supplement or replace natural insulin in the treatment of diabetes mellitus. It is the only effective treatment in Type 1 diabetes and may also be prescribed in Type 2 diabetes. Insulin should be used with a carefully controlled diet. Illness, vomiting, or alterations in diet or exercise levels may require dosage adjustment.

Insulin is available in short-, medium-, or long-acting preparations. Combinations of types are often given. People using insulin should carry a warning card or tag. They should be vigilant for signs of hypoglycaemia (low blood sugar), and should eat something sugary if they do develop.


Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Injection, infusion pump, pen injection.

Frequency and timing of doses 1–5 x daily. Usually 15–30 minutes before meals (short-acting); some forms given directly before or after eating. Exact timing of injections and longer-acting preparations tailored to individual needs; follow instructions given.

Dosage range Exact timing of doses is tailored to individual needs. Follow manufacturer’s instructions.

Onset of effect 15–60 minutes (short-acting); within 2 hours (medium-acting); 2–4 hours (long-acting).

Duration of action 2–8 hours (short-acting); 18–26 hours (medium-acting); 28–36 hours (long-acting).

Diet advice A special diabetes diet is necessary. Follow your doctor’s advice.

Storage Refrigerate, but once opened may be stored at room temperature for 1 month. Do not freeze. Follow the instructions on the container.

Missed dose Discuss with your doctor. Appropriate action depends on dose and type of insulin.

Stopping the drug Do not stop taking the drug without consulting your doctor; confusion and coma may occur.


Seek immediate medical advice. You may notice symptoms of low blood sugar, such as faintness, hunger, sweating, and trembling. Eat or drink something sugary. Take emergency action if seizures or loss of consciousness occur.


The most common side effect of insulin is hypoglycaemia (low blood sugar), which may cause symptoms such as dizziness, sweating, weakness, and confusion. If such symptoms occur, you should eat or drink something sugary and seek immediate medical advice. Irritation at the injection site is also common. Other, less common adverse effects include dimpling of the skin at the injection site and eyesight problems; discuss with your doctor if these occur. Serious allergic reactions (itchy rash, facial swelling, and breathing difficulties) are rare; if they occur, you should seek urgent medical attention.


General note 1 Many drugs, including some antibiotics, monoamine oxidase inhibitors (MAOIs), and oral antidiabetic drugs, increase the risk of low blood sugar.

General note 2 Check with your doctor or pharmacist before taking any medicines; some contain sugar and may upset control of diabetes.

Corticosteroids and diuretics may oppose the effect of insulin.

Beta blockers may affect insulin needs and mask signs of low blood sugar.


Be sure to tell your doctor if:

· You have had a previous allergic reaction to insulin.

· You are taking other medicines, or your other drug treatment is changed.

Pregnancy No evidence of risk to the developing baby from insulin, but poor control of diabetes increases the risk of birth defects. Careful monitoring is required because insulin requirements may change.

Breast-feeding No evidence of risk. Adjustment in dose may be necessary while breast-feeding.

Infants and children Reduced dose necessary.

Over 60 No special problems.

Driving and hazardous work You must inform the DVLA you are taking insulin. You must check your blood sugar before driving and follow DVLA guidelines. Avoid driving or dangerous activities if you have signs of low blood sugar.

Alcohol Avoid. Alcoholic drinks upset diabetic control.

Surgery and general anaesthetics Insulin requirements may increase during surgery, and blood glucose levels will need to be monitored during and after an operation. Notify your doctor or dentist that you are diabetic before any surgery.


No problems expected.

Monitoring Regular monitoring of blood sugar levels is required.