Thinking of moving from MDI to a pump?

I don’t do fast, when it comes to making big changes, and that includes managing blood glucose. I like to weigh the pros and cons, knowing that in a bed of roses there are hidden thorns.

Anyway I was wondering how basal rates are calculated from a long insulin such as Lantus to a pump using a rapid insulin. I found this page from Washington University Pediatrics to be quite informative. Some stuff is probably out of date as technology has a way of running ahead of documentation. I just thought I would share.

I am just thinking about making the change. I am leaning towards the T: slim X2 and the OmniPod Dash, but I haven’t looked at Medtronics. Here’s a screenshot comparing pumps.

This is most likely not information you are looking for at this time but is related. For me, long-acting insulin caused repeated lows at night so I proved that out to my stubborn Endo and finally total ditched Lantus and Levemir and went to using only fast-acting Humalog several years ago and never looked back. My BG became amazing, being able to hit 100% TIR for a full month period, with a lot of obsessive looks at CGM, and my A1C dropped into the mid 5’s and an SD of 20. I am strictly MDI. The major difference I might have with you is that I have a digital insulin pen that doses in 0.1 units.

This is just an option you may want to try, as you are weighing all the pros and cons before a switch to a pump.


As an initial approximation, you can take your total dose of long acting insulin per day and divide it by 24 to get an hourly rate. For example, if you dose Lantus at 12 units per day, you can start your personal experiment with the pump by setting 0.5 units/hour as your starting basal rate.

If you want to build in a safety factor, then deliver 80% of the above calculation, in this example, then deliver 0.4 units/hour to start.

There are people who prefer a flat basal rate (I think Dr. Ponder is one of them) but most of us end up tweaking our basal rates according to the time of day. My basal rates are higher in the early morning to account for the circadian effects of dawn phenomenon. Then my basal rates are lower in the late afternoon to avert hypos that seem to typically show up for me then.

I would start with the flat basal rate and then customize per your unique needs. I’m hoping that you use a CGM as this would require a lot of finger-sticking if you did not.

Good luck! Adopting new treatments is a healthy habit, in my opinion. If it goes well, your health and quality of life improves. If it does not, at least you know from actual experience and can write that idea off for yourself.


That’s an interesting idea, CJ. If I understand you correctly, in addition to the usual meal-dosing, you deliver many correction doses each day to steer your trending glucose levels. How many of these correction doses do you typically deliver and what is a typical dose size?

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The image you shared has outdated info - but great that you are looking into it! I have been pumping for about 23 of the 26 years I’ve been diabetic. I currently use the Tandem system and have had A1cs between 5.5-6. It’s been fabulous and I can’t imagine not using it.

Check this link out for updated info:


I think what is interesting is that no one has alluded to going on the pump success may partially be the result of dropping the Lantus/Levemir which affects BG much differently than the fast-acting insulins normally used in pumps. I, like you am OMAD and light on the carbs so I normally need between 0-4 units between 4 AM and 6 AM, 3.2 to 4.3 units at 9:15 AM Lunch Pre bolus depends on planned meal but between 5.2 units to 8.9 units and meal is at 12:20, roughly 4 units at 2:10 PM, up to 2.6 units at 4:10 PM and 0-3.8 units at bedtime.

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Thanks, Allison, I assumed it wasn’t up to date. That’s been a problem ever since the internet became a thing, a lack of revision.

I am new to MDI just 10 months as a type 2 who has progressed through several stages, from only diet and exercise to the present, still careful about diet and exercising plus half the dose of Metformin I was one, slightly reduced Lantus and premeal Humalog.

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When I transferred to a pump. I did like what was already suggested. I divided by 24 and put that in. But my rates at night are a lot lower than days. My nights vary but are about .75 units per hour at night. I bump it to .85 at 5 am because I have predawn rise at that time.
My days are higher most of the time at 1.1 per hour.
It takes time to figure out the rates.
My basal rates are lower on my pump than they were on injections.
I was injecting 2 doses of lantus 15

units but I went to a total of 25 on my pump.

With ciq I am running about 28 units a day on average of basal insulin. And 25 for bolus.

I have taken a break from my pump several times, and there are pros and cons. It feels more free to not have it on me, but I have much better control with it, and I need to take 10 injections/ corrections a day on injections

Split dose for lantus is 2 plus one injection per meal, that’s already 5, and 5 corrections because I just can’t let a high sugar be.

It’s not for everyone and pumps are expensive. For me it’s worth it.

Good luck.

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I might be confused, but your body still produces some of its own insulin, doesn’t it? Could someone who produces no insulin at all still get by on just fast acting insulin using MDI?

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I believe that is what a pump does for a T1. It is micro-dosing fast-acting insulin at a programmed interval. MDI multiples on one insulin are just not as frequent as pump doses.

Probably a bit, T2DM is a progressive disease driven by insulin resistance by glucose receptors.
Stage 1 - BG is within range, but insulin levels high. Many have reactive hypoglycemia causing lows between meals.

Stage 2 - BG elevates to what is considered pre-diabetes as the Beta cells cannot secrete enough insulin to overcome resistance.

Stage 3 - BG is becoming dangerously high, insulin resistance increases, person has decreasing energy as cells are starving for fuel, glucose may be spilling into urine. Various diabetic complication may begin.

2 and 3 stages can often be treated with a carb restricted diet, daily exercise with or without oral or injectable drugs, not insulin as insulin levels are high.

Stage 4 - As Beta cells weaken from over work the type 2 DM will need to add drug therapy to diet and exercise. Some of these drugs will stimulate the Beta cells to secrete even more insulin.

Stage 5 - At this point oral and non-insulin injectables have limited effect because the Beta cells are worn out and dying. At this point the T2DM may start using a basal insulin.

Stage 5 - Drugs and basal insulin are not enough and the T2DM begins bolus insulin before meals.

Not all type 2 diabetes will progress this far. In my 30 years since diagnoses I have carb restricted, daily exercise and learned which foods I should avoid using my meter. This gave me normal or near normal BG for 10 years. Then BG spiked, eating nearly zero carbs and exercising more did nothing. I was prescribed Metformin. Over the years the dose was increased to the max. Then I was prescribed Lantus. In the fall of 2020 I noticed my fBG and other tests was rising.

My HbA1c in December was a full percentage point higher than the previous one 6 months before. My new doctor and I decided it was time for MDI and a CGM. I was using syringe and vials, change to pens because of a lack of syringes locally (COVID related supply problems?)

Anyway, it was rocky for a while. I consumed more glucose tablets in the night then in 30 years. I also would have exercise induced lows. My BG could be 140+ and 15 minutes of brisk walking or bicycling or yard work could cause it to plummet to a hypo. Decreasing the Metformin has really helped with hypos.

Being on MDI as a type 2 DM has challenges as I suspect I still secrete some insulin, insulin resistance and sensitivity rises and falls. My total daily insulin basal/bolus is about 33u with 25u basal and 6 to 8u bolus. I know this ratio is not the usual for T1DMs. My last HbA1c was 5.3% and my time in range is 98 to 99%. Usually the 1 -2% is an occasional low, not very low.

Type 2 DMs in stage 5 should probably be called Non-immune Insulin Dependent Diabetics.

Well, I gotta go, Marilyn, stuff to do before my Friday 30 mile group ride. I hope I didn’t bore you.

Actually my comment was directed to CJ114, but I found what you wrote interesting. I hope that you enjoyed your ride!

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It was splendid, 5 riders outbound into a light headwind, and because of a front headwind on the way back. 33 + 3 miles, I forgot to start Garmin, BG 130 to start, 108 to finish, no added carbs just water.

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Sorry, I was up early and didn’t pay attention.

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Just curious - Did you test BG 30 minutes or so after finish and if so can you divulge? Just a guess, but I would expect back to your starting 130 and potentially a little higher.

Sure, I have a Dexcom G6 so that is pretty easy. I want to give you several readings from ride start to finish and then 1 hr 17 minutes post ride.
Start 07:00 130mg/dl
07:08 133
07:43 123
Finish 09:06 108
09:23 108
09:38 116
09:58 103
10:23 97

The bump up at 32 minutes past the finish is common, but then BG continues to decrease as the leg muscles suck up glucose to replenish glycogen stores.

Thank you, this interests me because I follow the same pattern, but my 09:38 would have landed in the 135-140 range for a similar intensity exercise, and yes, a drop would then ensue.

This isn’t a scientific way of measuring, but when I got off lantus a number years ago and onto the Omnipod, my endo took my total average insulin usage in a day (55 units) and divided that in half and used half for bolusing and half for basal. That worked fairly well to get started. So my total basal when I started was 27 units. Today I’m at 23.5 so it was close. With the pump I adjust basal only occasionally but you will want to do it fir the morning phenomenon and for trends of highs or lows

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That is a pretty standard ratio Basal:Bolus of roughly 50-55% basal to 45 to 50% bolus. However, as a type 2 DM on MDI that doesn’t work well for me. My basal:bolus ration is 81%:19%. My worn out Beta cells probably skews things by secreting a bit of insulin, and I have a tendency, as a T2DM, to varying insulin resistance.

Yesterday, I didn’t do my daily exercise which resulted in high BG than usual, especially this morning. Same food same Lantus/Humalog units, actually did a slight correction on the Humalog. Without daily exercise insulin resistance lifts its ugly head, “Hey, remember me?”

Anyway, I been reading through the user guide for T:Slim X2 and think I could make good use of setting the odd basal rate I use. On Lantus, I divided it into 3 doses, waking 10u, 30 min before lunch - 10u and 30 minutes before dinner 5u for a total of 25u. When I am going to do a long bike ride I cut the morning dose to 6-7u giving the rest at ride end.

This has worked very well in leveling out my BG curve on Dexcom.

If I make the change I think I would like the pump to do basal until I am comfortable with it, while I do pre-meal and corrections manually. Then perhaps going to C-IQ. As I said, I am slow and cautions about accepting new.

Thanks for the update Luis. I’m sorry I didn’t realize you were type 2. I’m type 1. I know it is a different scenario for you than me and thanks for the info. I’ve had to go back to injections once when I ran out of pumps (Omnipod) and it was scary to think how accustomed I have become to the technology. I managed but was happy when the pumps arrived in two days.