Basal insulin (delivered via a pump, or long-acting insulin delivered via injections), is the background insulin that keeps blood glucose levels steady between meals, and overnight. Well-tuned basal insulin is the cornerstone of optimal blood glucose management. Think of it like building a Lego castle with a toddler. They want to build it one brick wide and as high as it can go. You know that without a solid foundation upon which to build, the castle will wobble and crash, so you create a firm, four-brick base and build up from there. Basal is this solid foundation. Meal insulin and corrections are the bricks that can be steadily placed on top, manipulated as needed, to build a stable blood glucose. Basal insulin usually makes up about 40-50% of total daily insulin doses. If your basal is much more than this, it may be compensating for inaccurate carbohydrate or correction factors. If it is much less than this, you may find yourself doing a lot of corrections! So why does basal become such a beast? Let’s look at a couple of examples from my clinic: Example One – Gaston, pumper for 8 years Gaston has a sandwich, apple and a coffee for lunch every day, totalling 60g of carbohydrate for the meal. However, Gaston calculates the carb count for the meal based on a different brand of bread, and so he boluses insulin for only 45g of carbohydrate, rather than the carb count for the new brand of bread his partner has started buying. Gaston noticed that he had high blood sugars in the four hours after lunch each day, and assumed that this must be an issue with his basal rate on his pump. To fix this, he increased his basal rate in the afternoon. What was Gaston’s mistake here? Gaston has changed his basal rate to compensate for a high blood glucose that was actually caused by inaccurate carbohydrate counting. What should Gaston do? Gaston could likely do with some carbohydrate counting re-education. He would also benefit from having his educator check his carbohydrate ratios. Gaston feels that he may have been changing his basal rates to compensate for a number of issues, so he has asked his educator to help guide him through a ‘basal test’, which involves some short fasting periods, to dial in his basal rates properly. Example Two – Belle, injections for 12 years Belle takes long-acting insulin (Levemir) at 9pm each night. Lately, she has been finding that her blood glucose level has been creeping up mid-afternoon. She is not sure why but works out that she can fix it with a correction dose or two of rapid-acting insulin before dinner. Belle’s long acting insulin only makes up 30% of her total daily insulin. What was Belle’s mistake here? Belle has given a correction dose of rapid-acting insulin to compensate for a lack of basal between 3pm and 9pm. Unfortunately, her long-acting dose wasn’t lasting the full 24 hours. What should Belle do? Belle would benefit from discussing the action of long-acting insulins with her educator, and undergoing some ‘basal testing’. Together, Belle and her educator may look to determine if it is appropriate to split her Levemir dose across two injections to get better overall coverage. Transforming basal: from beast to beauty Gaston was quick to blame his basal for inaccurate bolus calculations, and Belle didn’t know her long-acting might not cover her for the whole day! Knowing your basal and adjusting it accurately is the key to your solid blood glucose foundation. When should you look to adjust basal rates/long acting insulin doses?
If you are consistently waking up high/low or you are high/low during times where there is no rapid acting insulin on board (three hours after meals or snacks);
Before and/or after exercise (consider adjusting downwards);
During periods of illness (consider adjusting upwards).
When is something else to blame?
If your blood glucose is consistently high/low in the 2-3 hours after meals/snacks, you need to check your carb ratios and bolus calculations;
If your blood glucose is consistently high/low in the 2-3 hours after a correction dose, you might need to change your correction factor.
Be our guest! If you feel you need help with your basal, get back to basal basics! You can learn more about basal testing and adjustment from your diabetes educator - call the Family Centre on 9446 6446 and we'll connect you up.