Diabetes mellitus is a disease of not enough insulin. It’s a story of pancreatic insufficiency when it comes to insulin.

In Type 1, there’s no insulin produced. This is an absolute insulin deficiency.

In Type 2, the gradually failing pancreas doesn’t produce enough insulin to meet the body’s increased requirements; in certain people, the body is a needy thing that becomes less and less sensitive to insulin over time, so more is needed of it. This is a relative insulin deficiency.

If diabetic ketoacidosis is a crisis characterised by a lack of insulin, why is it that both intravenous glucose and insulin are part of the treatment?

This is because DKA has two big issues:

1. Acidic blood pH because of too many ketones
2. Hyperglycaemia

Treatment with insulin corrects both of these. However, the hyperglycaemia resolves first. IV glucose gives more time to allow the insulin to keep suppressing ketones, thus addressing the acidosis as well.

References

1. Diabetic ketoacidosis. In: eTG complete [Internet]. Melbourne: Therapeutic Guidelines Limited (eTG November 2017 edition); 2017 Nov.