Insulin glargine

How it works

It precipitates as microcrystals in the neutral pH of subcutaneous tissue, producing a slow, relatively peakless release that gives a prolonged, steady basal insulin effect.

Prescribing in practice

• Hypoglycaemia is the principal risk; never administer intravenously and do not mix in a syringe with other insulins, as this alters its absorption profile.
• Be aware that different glargine strengths and biosimilar brands are not interchangeable unit-for-unit, so prescribe and switch by brand to avoid dosing errors.
• Insulin requirements may change with illness, weight change, renal impairment or altered physical activity, requiring dose review.

Monitoring

Monitor capillary or interstitial glucose and HbA1c, paying particular attention to fasting glucose and nocturnal hypoglycaemia when titrating the dose.

Counselling the patient

• Inject once daily at the same time each day and rotate injection sites within an area.
• Recognise and treat hypoglycaemia promptly, and never stop insulin during illness without advice.
• Store in-use pens at room temperature and spare cartridges in the refrigerator without freezing.

Evidence & guidelines

Basal insulin analogues are established in NICE guidance for type 1 and type 2 diabetes, offering comparable glycaemic control to NPH insulin with a lower risk of nocturnal hypoglycaemia.