Gliclazide: uses, low blood sugar risk and cautions

Gliclazide treats type 2 diabetes in adults when diet, exercise and weight loss have not been enough. The NHS explains that it works by increasing how much insulin your body makes, which lowers the sugar in your blood. It only has something to work on if the pancreas can still make insulin, which is why it is not used for type 1 diabetes.

It sits in the sulfonylurea family. Prescribers often add it when a person already takes metformin and needs more help, but it can also be used on its own. Your prescriber decides the combination.

The NHS describes tablets taken once or twice a day with water after meals, at the same times each day, usually long term. The emc leaflet for the modified-release Diamicron 30 mg MR tablet says to take it as a single dose at breakfast, swallow it whole without chewing, and always eat a meal afterwards. A food-first routine is part of using this medicine safely, not a detail.

The leaflet states the daily amount can range from one to four of those tablets in a single intake, up to a stated maximum, and doctors work out the figure for each person, particularly if other diabetes medicines are combined with it. Do not adjust it yourself.

Because gliclazide pushes insulin out whether or not you have eaten, the leaflet places hypoglycaemia first among its warnings and says the risk is higher in the first weeks. Symptoms it lists include headache, intense hunger, nausea, vomiting, tiredness, sleep disturbance, restlessness and aggression. The NHS adds dizziness and says to have something sugary straight away.

The leaflet describes situations that make it more likely: irregular or skipped meals, fasting, dietary changes, more exercise without extra carbohydrate, alcohol, other medicines, and severe kidney or liver problems. Untreated severe lows can lead to confusion, convulsions and loss of consciousness, so someone else should know what to do.

• Have sugar, a sugary drink or glucose tablets immediately, then a proper meal.

• If someone is unconscious, do not put food or drink in their mouth; call 999.

• Frequent lows or poor warning signs are worth raising with your diabetes team and may affect driving.

The NHS lists stomach pain and diarrhoea as common. The leaflet notes digestive effects are reduced when the tablet is taken with a meal. Rare problems include blood count changes (bruising, sore throat, fever), liver effects (jaundice, which usually clears on stopping), and skin reactions ranging from rash to angioedema or widespread blistering.

For anaphylaxis the NHS says call 999. For other serious effects call NHS 111. Vision can be briefly altered at the start because blood sugar is changing.

The NHS lists previous allergy to gliclazide or similar medicines, severe kidney or liver disease, acute porphyria, and pregnancy or breastfeeding. The leaflet also names miconazole, an antifungal, as a medicine not to combine with it. People with G6PD deficiency can develop haemolytic anaemia on sulfonylureas, and the leaflet says it is not recommended for children.

Older adults who also take beta blockers or sedating medicines may have weaker hypoglycaemia warning signs, according to the leaflet.

The leaflet sorts interactions into those that deepen lows (other diabetes medicines, sulfonamide antibiotics, clarithromycin, beta blockers, ACE inhibitors, fluconazole, ibuprofen and others) and those that push sugars up (corticosteroids, chlorpromazine, danazol, St John's wort and some asthma or labour medicines). Fluoroquinolone antibiotics can disturb sugar either way. The NHS also advises against combining it with weight-loss drugs such as semaglutide or tirzepatide without guidance.

Alcohol is not recommended because it changes diabetes control unpredictably. Driving is a matter of safety: do not drive when dizzy or drowsy, and ask your clinician about driving if you have frequent lows.

If you miss a dose, the leaflet says take the next one at the usual time and do not double up. Diabetes treatment is usually life long, so talk to your doctor before stopping. Gliclazide is prescription only in the UK; the emc lists brands including Diamicron and Xywin among generic products.