BMA Concise Guide to Medicine & Drugs


Brand names DIAGLYK, Diamicron, Diamicron MR

Used in the following combined preparations None


Drug group Drug for diabetes

Overdose danger rating High

Dependence rating Low

Prescription needed Yes

Available as generic Yes


Gliclazide is an oral drug for diabetes belonging to the sulphonylurea group. It stimulates the production and secretion of insulin from the islet cells in the pancreas. This promotes the uptake of sugar into body cells thereby lowering the level of sugar in the blood.

The drug is used to treat Type 2 diabetes mellitus, in conjunction with diet and exercise.

In conditions of severe illness, injury, stress, or surgery, the drug may lose its effectiveness necessitating the use of insulin injections. Adverse effects of gliclazide are generally mild. However, symptoms of poor diabetic control will occur if the dosage is not appropriate.


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

How taken/used Tablets, MR-tablets.

Frequency and timing of doses 1–2 x daily (in the morning and evening with a meal).

Dosage range 40–320mg daily (doses above 160mg are divided into two doses).

Onset of effect Within 1 hour.

Duration of action 12–24 hours.

Diet advice An individualized diabetic diet must be maintained for the drug to be fully effective. Follow the advice of your doctor.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take with next meal; do not double the dose to account for missed dose.

Stopping the drug Do not stop the drug without consulting your doctor; stopping the drug may lead to worsening of the underlying condition.


Seek immediate medical advice in all cases. If early warning symptoms of excessively low blood sugar such as fainting, sweating, trembling, confusion, or headache occur, eat or drink something sugary. Take emergency action if seizures or loss of consciousness occur.


Serious adverse effects are rare with gliclazide. Symptoms such as dizziness, fainting, confusion, weakness, tremor, and sweating may be signs of low blood sugar due to lack of food or too high a dose of the drug. If any such symptoms occur, eat or drink something sugary immediately and seek medical assistance. Other possible adverse effects include constipation, diarrhoea, nausea, vomiting, rash, itching, and weight changes. Discuss with your doctor if they occur. If jaundice develops, consult your doctor without delay.


General note A variety of drugs may reduce the effect of gliclazide and so may raise blood sugar levels. These include corticosteroids, oestrogens, NSAIDs, diuretics, and rifampicin. Other drugs increase the risk of low blood sugar. These include warfarin, sulphonamides and other antibacterials, aspirin, beta blockers, ACE inhibitors, and antifungals.


Be sure to tell your doctor if:

· You have long-term liver or kidney problems.

· You are allergic to sulphonylurea drugs.

· You have thyroid problems.

· You have porphyria.

· You have ever had problems with your adrenal glands.

· You are taking other medicines.

Pregnancy Not recommended. May cause abnormally low blood sugar in the new born baby. Insulin is generally substituted in pregnancy because it gives better diabetic control.

Breast-feeding The drug passes into the breast milk and may cause low blood sugar in the baby. Discuss with your doctor.

Infants and children Not prescribed.

Over 60 Signs of low blood sugar may be more difficult to recognize. Reduced dose may be necessary.

Driving and hazardous work Avoid such activities until you have learned how gliclazide affects you because it can cause dizziness, drowsiness, and confusion.

Alcohol Avoid. Alcoholic drinks may upset diabetic control increasing the risk of hypoglycaemia.

Surgery and general anaesthetics Notify your doctor or dentist that you have diabetes before undergoing any surgery.

Sunlight and sunbeds Avoid exposure to the sun and do not use a sunlamp or sunbed.


No problems expected.

Monitoring Regular testing of blood sugar control is required. Periodic assessment of the eyes, heart, and kidneys may also be advised.