Isophane insulin (alias NPH) is a standard long-acting human insulin for type 1 and type 2 diabetes. Long-acting human insulin analogues are also available, including insulin glargine that offers a practical benefit for some type 1 diabetes patients; and insulin detemir that offers no particular benefit. Uncertainties remain as to their long-term adverse effects.

Insulin degludec is another long-acting human insulin analogue, authorised in the EU for type 1 and type 2 diabetes patients. The comparative trials evaluating insulin degludec have not shown it to be more effective in controlling HbA1c than other insulins. This also applied to type 2 diabetic patients treated with long-acting insulin.

In addition to the adverse effects common to the other insulins, it is thought that there might be an increased cardiovascular risk.

Whereas in France all the other insulins are at a concentration of 100 units per ml, the new concentration of 200 units per ml for insulin degludec in pens exposes patients to medication errors as a result of confusion between the two concentrations, with the risk of overdose.

Given the lack of any proven benefit of insulin degludec, it is better to rule it out until the cardiovascular risk has been more clearly identified.

©Prescrire 1 June 2014

"Insulin degludec. Uncertainty over cardiovascular harms" Prescrire Int 2014; 23 (150): 149. (Pdf, subscribers only).