If someone using insulin reported persistent high blood glucose levels when they tested it, it would be very easy to simply increase the insulin dose. Before this is done, a number of 'physical' checks should be made.

Insulin storage
It is important to ensure that insulin vials and cartridges are kept out of direct sunlight, as this can damage the insulin and make it less effective. It is also essential that the insulin being used is not out of date.

As a rule, insulin that is actively being used should be kept at room temperature, as this can also help reduce the discomfort from administering the injection. It will remain stable and active for at least 28 days at room temperature.

Insulin that is not being currently used should be stored in a refrigerator.