My son believes his insulin pump can only deliver basal units or very small boluses for him. A meal bolus via the pump, 16 units of NovoRapid, does not work well and his blood sugar ends up high. If he injects using a flex pen instead for meals in similar conditions, his blood sugar is better regulated. He has tried changing the reservoir, infusion set, pump, etc. Is there any reason for this?

Boluses via syringe, pen, or insulin pump all work the same but the pump has an added option called extended boluses. Timing the bolus about 15 minutes before food also remains important to match the absorption of the insulin to the effects of the food on glucose levels. He may want to change to a different brand of fast acting insulin to see if that also matters; usually not, but sometimes, individual differences are important. The key is to look at pre-meal/pre-snack blood glucose levels and then also 1 to 2 hours after the food to define the effects. Sensor data is the best, if he has access to a CGM (continuous glucose monitor), but frequent monitoring will also provide such information.

The extended boluses from most pumps are extremely helpful, too. These are used when there is fat with carbohydrates in a meal or snack and slow down the delivery of insulin to match the glucose raising effect better. With fat and carbohydrates together, the food stays in the stomach longer, so the glucose levels rise about 2 to 4 hours after that food. The slower extended boluses deliver insulin over 30 minutes and this covers the 2 to 4 hour peak. You cannot do this with injections without taking multiple injections. So, I would go back to your diabetes team and review this in some more detail.

SB