How can I adjust insulin dose to improve glucose control?
Consider the individual with type 1 diabetes (T1DM) on a basal-bolus insulin regime. The dose of basal insulin will significantly determine fasting (pre-breakfast) blood glucose (BG) levels, whilst breakfast, lunch and evening meal doses of rapid-acting (prandial) insulin will have an important effect on pre-lunch, pre-evening meal and pre-bedtime BG readings respectively. Table 1 outlines management of BG readings that are higher or lower than desired. Target BG readings are those suggested by NICE but should be individualised, not least with respect to risk of hypoglycaemia and degree of hypoglycaemic awareness.1
For the person with T1DM taking a twice daily mixed (biphasic) insulin (combined intermediate-acting plus rapid-acting insulins) similar targets and dose adjustments apply. The morning dose of mixed insulin will determine pre-lunch and pre-evening meal BG readings whilst the evening dose will determine pre-bedtime and fasting BG levels. The regime is inherently less flexible than the basal-bolus regime and in the requirement to avoid hypoglycaemia less tight glycaemic control may have to be accepted.