I am new to Dexcom CGM. I want to eat a fruit salad in the morning. I am wondering, after I bolus, how much of a drop should I wait before eating? I am in Canada, so for ie: if I’m at 5.0, what number should I wait to see before I start eating?
Thank you!!!
PS I’ve been Type 1 for 5 years, but I have been in burnout mode for about 2 years. I’m just getting back on track. I’m now on a pump and cgm. I appreciate positive feedback please.
It depends. I know that I am relatively insulin resistant in the morning so I can err on the side of a longer prebolus time, up to an hour. Here are two recent mornings and my CGM trace.
The green stripe ranges from 65-120 mg/dl (3.6-6.7 mmol/L). I bolused at 9:15-9:30 a.m. each morning and delayed eating 45-60 minutes. You can see the steady downward trend around 10:15-10:30 a.m. as well as the post meal bump.
Similar results in this trace, too. So, in each case I was riding around 100-120 mg/dl (5.6-6.7 mmol/L) and dropped to about 80 or 100 mg/dl (4.4-5.6 mmol/L). So that was about a 20 point drop or around 1 mmol/L. If my starting BG was higher I might wait for a 30 point drop or around 2 mmol/L.
I shorten this waiting time at dinner to about 30 minutes, but still look for a similar drop or bend. I see pre-bolusing as one of the only ways to get the modern insulin a chance to catch up to the food. The CGM is a great tool to dial in your unique digestion timing. Good luck!
It is important to understand that pre-bolus blood sugar drop will be proportional to not only timing, but dose. If you are like Terry and doing low carb with low doses of insulin you will see slower drops due to this effect. If you are eating high carb breakfasts with (relatively) high bolus doses you may see faster and more dramatic drops. A pre-bolus of 15 minutes may be right at the edge, it really depends.
And I look at morning as a special case. I actually bolus immediately upon waking even if I won’t immediately eat. I need insulin just to offset my Darn Phenomenon. In general, eating a high GI food (like fruit) will have a nearly immediate effect on me, within minutes so a pre-bolus is appropriate (although I rarely eat any high GI foods). Usually a rapid insulin will start to have an effect (onset) in 15-30 minutes. If I am adding in a correction I will also back it further off, perhaps even to 30-45 min or the 45-60 min that Terry uses. That gives the correction time to normalize my blood sugar.
So it really depends, just remember that both the timing and dose size effect the amount your blood sugar will drop over the 15-30 minutes that you might pre-bolus.
Unlike Terry and Brian, I can (and do) manage a large number of carbs in the morning including an apple at the end of the meal. I will bolus no more than 5 minutes before eating and sometimes will bolus with the first bite of my eggs. Each of us is different. I would suggest adding the fruit salad to your meal with the appropriate additional insulin and see what happens. You may be pleasantly surprised. But if you spike and come back down at 3 hours you’ll know that you have to take your insulin a little earlier. If you spike and don’t come back down, you may have to bump up your bolus.
Maurie
Thanks all for your comments. I was surprised to see how long it took for me to drop from 6.5 to 5.5…almost an hour. I may try bolusing less, then doing my workout while I wait for the drop (monitoring closely, of course, with my CGM) to be more efficient.