One of the things you hear a lot of with Extended Boluses is "it's trial and error", which I don't dispute there's no way round that. The thing is to determine if something is an error and the cause of that error you have to know what success looks like and that's something, as I refine my Extended Bolus technique, I've realised I don't know what a 'perfect Extended Bolus' would look like. So does anyone who's got a good technique down want to share, what happens when your Extended Bolus works? Observations from my own trial and error. 1) Too Much Insulin Up Front, or the Extension is Too Short This is fairly easy to recognise. Your Blood sugar dips below your starting point without even the hint of a spike from the food. You treat the hypo (even preemptively at above 4.0mmol/l) and then the treatment sends your Blood Sugar into the stratosphere because the Food Spike hadn't actually hit yet, and the Insulin you intended to deal with that Spike was essentially eliminated by the Hypo treatment. 2) Too Much Insulin in the Tail, or the Extension is Extended for Too Long This one initially looks like you haven't taken enough Insulin. Your Blood Sugar starts climbing and climbing, if you correct your blood sugar drops like a rock because you did set the correct dose, it just hasn't arrived yet, and when it does arrive it makes the Correction you just took unnecessary*. Let's say you were patient and didn't correct. Instead, your blood sugar would climb and climb until suddenly dropping off a cliff when the required Insulin finally arrives (obviously this will vary a lot depending on how in sync your carb and correction ratios are). *I know hypothetically your Bolus Calculator should prevent this from happening, but I find the Bolus Calculator, in general, less reliable when Extended Bolus miscalculations have occurred.