How do I best split the doses of my insulin?

It may take a little experimenting and consulting with your health care team to figure out how to best mix rapid-acting or regular and intermediate-acting insulins. The ratio may change until you are getting the results that best suit you. You may find it convenient to buy a premixed insulin, such as a 70/30 or 75/25 mixture. Or you may prefer to split and mix the doses yourself. This lets you change the amounts of rapid-acting or regular and NPH independently of each other. You may find this helpful when trying to account for activity level and food intake.

If you are using a two-shot plan using split and mixed doses of intermediate-acting and rapid-acting or regular insulin, you will need to keep close tabs on your body’s response. This means that you need to monitor your blood glucose levels before and after meals. You may need to monitor at other times as well. A two-shot program gives you better coverage than a single-shot plan but still keeps you closely tied to a regular meal schedule and a regular pattern of activity. This is because you cannot make short-term adjustments in longer-acting insulins. Only rapid-acting or regular insulin can be adjusted immediately to respond to a blood glucose level or change in schedule.

If you find that your blood glucose level is fine at bedtime but high in the morning, you may want to move your evening insulin shot from dinnertime to bedtime. This will make insulin available a little later during the course of the night to keep your glucose levels in range. Make sure that your glucose levels are on target during the evening hours if you try this adjustment.

You may find that you have low blood glucose in the early morning (around 2 or 3 a.m.) with the two-shot plan. If this is the case, think about a three-shot plan. With this, you would give yourself a mixture of rapid- or short-acting and intermediate-acting insulin at breakfast, a rapid- or short-acting insulin at dinner, and an intermediate-acting insulin at bedtime.