’Twas the High Blood Sugar Before Christmas: The 5-Hour Humalog Rule

’Twas the night before Christmas,
And the glucomter was beeping,
Ma’s blood sugar was high,
And Pa wouldn’t be sleeping.

Christmas Eve 2011. The smell of parsnips and pumpkin pie still filled the air. The clock struck nine. Nicole’s glucometer went ‘beep.”

“Oh, oh,” said Nicole

Under the glow of Christmas lights I glanced down at the glucometer.

31.2 mmol/L. (561 mg/dL).

“Pumps not working again,”I said.

“Humbug!” said Nicole.

“No,” I replied. “Humalog!”

Nicole had been using an insulin pump for about two years. As we’ve related in previous posts, the pump had become unpredictable due to scar tissue. The pump would be pumping minute drops of insulin into her abdomen without fail for about 24 hours. Then it would suddenly stop. And, without those minute, fast-acting drops of Humalog, her blood sugar climbed high. The pumpkin pie probably didn’t help either.

Interestingly, today, with her low-carb diet, we’ve never, ever seen a blood sugar over 20 mmol/L even when everything goes wrong. But back to that high-carb Christmas Eve in 2011….

We’d spent hours upon hours being trained at the big city hospital in how to use the insulin pump. None of the instructions made too much sense to me. I would question the nurses and get confusing answers back. The type of answer that made me realize they either didn’t understand my question or didn’t know the answer.

Per instructions, Nicole immediately injected 5 units of Humalog into arm. She then tore out the pump and went through the process of replacing the tube, needle and vial of insulin.

We wait edan hour and checked her blood sugar. Still high! So she took another unit of humalog. Wait another hour, take another unit. Not wanting to have to get up and go to sleep every hour, we watched A Christmas Carol. I stayed awake. Nicole fell asleep.

By 1am her blood sugar had fallen below 6mmol/L. Merry Christmas!

By 2am her blood had dropped past 2mmol/L. Break out the cider.

By 3am she was high again. Not 30mmol/L. Maybe 10 mmol/L. We had enough and decided that below 13 mmol/L was good enough. We settled down for a short winter’s nap.

That’s how life used to be like – holiday or not.

It wasn’t until we read Dr. Bernstein’s Diabetes Solution that we learned a sane way to use synthetic insulin injections to cover high blood sugars. In Chapter 19 (“Intensive Insulin Regimens”) Bernstein writes: “Never cover an elevated blood sugar if you have not waited for the last dose… to finish working. After all, if two doses are working at the same time, your blood sugar can drop too low… the rapid acting insulins continue their action for only 5 hours after injection.”

This changed everything for us. It partly explained why Nicole typically went low when she corrected a high blood sugar. Instead of giving small doses every hour, she needed to give ONE carefully calculated dose and wait five hours.

For example, let’s go back in time to that Christmas in 2011. Pretend I’m Jimmy Stewart in “It’s a Wonderful Blood Sugar”…

Nicole’s blood sugar had hit 30.1 mmol/L (541 mg/dL). It should be 4.7 mmol/L. That means she needed to decrease her blood glucose level by 25.4 mmol/L (457 mg/dL).

We now know that 1 unit of Humalog puts Nicole’s blood sugar down 3 mmol/L. So… 25.4 mmol/L divided by 3 = 8.4 units of humalog.

Now, since her blood sugar is so high, we can safely up that to 8.5 or even 9 units. For whatever reason, we find the higher the blood sugar, the less effective the insulin.

Now, instead of just jabbing all that insulin into her arm, Nicole would split it up into 3 separate doses of 3 units each. One in one arm, another in another arm, another in the leg and another in a partridge in a pear tree.

It’s 9pm right now. Set the alarm for 2am. 5 hours later. No staying up doing a Christmas Eve blood sugar vigil. Next best thing to insulin for getting blood sugar down, is getting some sleep. We’ve well tested that dose. We know she’s not going to go low. And there’s nothing else we can do until 2am.

Come 2am, she’d check her blood sugar again. It’s likely it might still be a bit high. Correcting from such a high blood sugar is tricky business. It’s hard to hit the bull’s eye from 500 meters away. It’s like  a hole-in-on at golf. Just doesn’t happen very often. Par, for such a high blood sugar, is 2.

Her 2am blood sugar might have dropped to 6.2 mmol/L. So she still needs to drop another 1.5 mmol/L to reach 4.7 mmol/L by Christmas morn’. So she gives herself another 1.5 divided 3 = 1/2 unit of humalog. She injects directly into the muscle tissue. This speeds up the process even more and knocks an hour off the 5-hour wait.

So simple. So mathematical. We’ve been doing this now for over three years. It’s taken all the fear out of correcting high blood sugars for Nicole. If only we had known that fateful Christmas Eve in 2011. Things would have been different that Christmas morn.

She sprang from her bed, and jabbed her finger with glee,
Her glucometer displayed a sweet four point three.
And I heard her exclaim, as she wrote it all down,
“Merry Christmas to me, no hypoglycemic frown.”


The five-hour rule is even more true for slower-acting insulin like Regular, which Nicole uses to cover meals. Sometimes, of course, it’s hard to keep meals five hours a part. In a future post I’ll share a way to safely make a correction only four hours after a dose of Regular. Until then you might like to read about why we ditched the insulin pump for good and how things went.

Nicole’s HgbA1C is currently 5.0%. Better than most non-diabetics. If you have type-1 and would like some help with getting your blood sugar under control. please contact me. I’m offering inexpensive telephone coaching. Send me an email or call for more details.

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