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You only need a few days of living with type 1 diabetes (T1D) under your belt to realize just how powerful insulin is: It has the power to both keep you alive for another day and threaten your life on a daily basis.

Somewhere in the middle is the perfect dose your body needs in response to more than three dozen variables that can affect blood sugar levels and insulin needs on a daily basis.

Getting the right basal, or “background,” dose is a critical part of staying healthy and sane.

While a single unit or two of extra insulin can be downright dangerous, not having enough insulin in your bloodstream can leave you feeling like you’re failing at the biggest (and most constant) test of your life.

Most people with T1D had their basal rates set for them by a healthcare professional at diagnosis or again when they started on a device like an insulin pump.

But many don’t dare or don’t think to adjust their own basal rates over time — which is a shame, because doing so can be a great path to improving glucose control.

Here are four very common yet subtle factors to be aware of that can require some fine-tuning of basal/background insulin doses.

It’s very easy to conclude that constant lows and frequent rides on the “blood sugar roller coaster” actually mean you need less insulin, but the exact opposite is often the case.

When you’re not getting enough basal/background insulin, the foundation of your “house” is off-kilter, and you’re probably trying to fix it by taking constant correction doses after eating to get back into your goal range.

This is about as helpful as throwing a couple bricks under one corner of your house’s lopsided foundation.

New research shows that the conventional wisdom of a 50/50 basal:bolus insulin ratio isn’t universally applicable. Our basal needs are individual and change over time.

Let’s imagine you’re taking 3 units of rapid-acting insulin via correction doses every day, spread throughout the day.

It’s not the same as 3 more units of your basal insulin, because those long-acting doses are delivered in a smaller drip, drip, drip over the course of several hours.

When you start stacking constant correction doses on top of mealtime doses, you run the risk of low blood sugars.

Then, of course, if you’re overtreating those low blood sugars by ingesting too much sugar, you’ll bounce up into the 200 mg/dL range again. Then you try to correct the high, and the roller coaster continues.

Tip

Talk with your doctor about increasing your background/basal dose by 1 to 2 units. See how things go for a few days, and make another small increase if needed.

For pumpers, this can be done by making a small increase in all basal rates that add up to a total of 1 or 2 units per day, or it can be focused on a large chunk of the day.

Keep in mind that in some cases, basal rates may be set too high. If frequent hypoglycemia is your problem rather than high blood sugars, it’s definitely worth a round of basal rate testing to see how your background insulin performs on its own.

See more on basal testing below.

Allow me to get a little personal in an effort to demonstrate just how much a little background stress can affect your basal insulin needs despite your body weight or eating habits.

In early 2019, I weighed about 120 pounds and was taking 10 to 11 units of long-acting insulin once a day.

By May 2019, I had begun the process of divorcing my husband and finding somewhere temporary to live while we figured out how to separate our lives, sell our home, and acquire more permanent housing. All while also juggling the needs and care of our two young children.

By August 2019, I still weighed 120 pounds but the background insulin dose I needed gradually increased from 10 to 15 units a day in order to stay in my goal blood sugar range.

Clearly, I was stressed.

Note that increasing my background insulin did not cause me to gain weight. Instead, it merely helped me maintain blood sugar levels in my goal range.

I was driving between three different towns, waking up at the crack of dawn in my “temporary housing” that didn’t have room for children, driving to our family home to get them ready for preschool, then getting myself to work, yada yada yada… while also juggling being the “realtor” selling our home without an agent, and working things out with my soon-to-be ex-husband.

The stress wasn’t something you might’ve seen on my face. I was still having fun with friends and my kids despite the chaos.

But my default stress level — which means my cortisol and adrenaline levels — was far higher than usual.

Compare 15 units at 120 pounds to today, 2 years later: I weigh more at 125 pounds but my background insulin dose is only 9 units.

Why? My stress level is much, much lower.

Tip

Be mindful of your dosing needs if you just experienced a significant shift in your day-to-day stress level.

A change in your home, your work, the loss of a loved one, dealing with a new medical condition, Thanksgiving with your in-laws, etc., will all affect your stress levels.

Again, talk with your healthcare team about increasing your basal insulin doses by 1 or 2 units. See how things go for a few days before making another small increase.

It’s extremely normal to see your weight fluctuate throughout the day or the week by a few pounds due to water retention, menstrual cycles, etc.

But when that fluctuation turns into body fat, it means one clear thing: increased insulin resistance.

And increased insulin resistance means you’ll probably need a bit more basal insulin to stay in your goal blood sugar range.

Personally, I weigh myself no more than once a week, and I can usually tell if I’m up a few pounds based on how comfortably my favorite pants fit.

Allow me to share another personal example: In October 2020, my 5-year-old had major surgery on her bladder and kidneys.

The surgery was significantly more intense than the surgeons anticipated, and her postop recovery went from expecting 1 week of couch rest to nearly 5 weeks before she was stable enough to return to school.

I had a lot on my hands “doctoring” her most days while also trying to juggle work and another young kiddo.

At the same time, there was an attempted murder at the condo I own and rent out. (Not kidding! Holy moly!) The stress and demands on my schedule during this time meant my entire food and exercise routine was thrown out the window.

I gained 4 or 5 pounds during those 2 months amid this chaos, but it snuck up on me because of those little fluctuations on the scale that I was used to being temporary.

Suddenly, I realized my baseline body weight was no longer 125 pounds but now 129.5 pounds.

You wouldn’t have noticed it much by looking at me, but those 4.5 pounds had a big impact on my background insulin needs.

I raised my background dose from 9 to 12 units until I was able to shake off those extra 4.5 pounds by returning to my usual low carb eating routine.

Tip

If you’re noticing that your pants are fitting a bit more tightly, take a look at how your blood sugars have been lately, too.

If you’re hovering above your goal range between meals and overnight, chances are you and your doctor may need to make a few basal rate tweaks of at least 1 or 2 units.

Again, see how those changes work for a few days before making another small increase.

The nutrition part of this is pretty obvious, especially over the winter holidays when we’re all eating heavier foods and more indulgent treats.

Boosting your background insulin dose can make a big difference in your body’s ability to handle the extra carbs and dietary fat of heavy meals — even though you’re taking a bolus dose of insulin to cover it.

Basal insulin does help your body manage the food you’re eating. It’s all connected!

But the activity level thing can be a little sneakier.

Daily exercise? I get plenty, no matter the season or the amount of snow outside. I’ve learned that even just small changes in activity levels can have an impact on your background insulin needs.

For example, as long as the temperature is above 10 degrees where I live in Vermont, I take my dog on 2-mile walks twice a day. In the winter, I also run or walk another 3 miles on my treadmill, along with a mini strength training routine most days.

One would think that’s plenty of exercise and my body shouldn’t need more insulin in the winter with that much activity, right?

Wrong.

It’s important to contrast your winter activity level with your activity level during the warmer months.

In the warmer months, I am jumping rope instead of walking or running on the treadmill, and jumping rope is definitely more of a full-body workout than jogging.

In free time with my kids, I take them to empty parking lots where we can scooter and ride our bikes. Plus I swim with my kiddos in the pool, and usually go on a third evening walk several nights a week with my boyfriend and pup.

That’s a big change from my winter routine.

Tip

When winter hits, keep a close eye on your blood sugars and your frustration level with frequent highs after meals.

Chances are, you’ll need a boost of 1 or 2 units in your background insulin doses, increasing again after a few days as needed. This is especially relevant during the holidays when everyone is cooking extra yummy things, and there’s a constant assortment of treats around.

Remember that your background insulin does help with your body’s ability to manage the food you’re eating.

Periodic basal insulin testing is essential, but it’s also pretty tedious.

What it entails is trying out your basal insulin in a “controlled environment” for a few days to see if your current background dose is keeping you in range without the variables of food or other insulin on board.

“In the absence of food, exercise and mealtime/bolus insulin, basal insulin should hold the blood sugar steady. Any significant rise or fall in blood sugar during a fasting basal test probably means that the basal rates need to be adjusted — even if the blood sugar winds up near normal by the end of the test,” according to the Pennsylvania-based virtual clinic Integrated Diabetes Services.

To start basal testing, you wait about 4 hours after your last meal and bolus insulin dose, and then check blood glucose levels every hour or two, or record the readings on your continuous glucose monitor (CGM).

The test has to be halted if your blood glucose rises too high or drops too low.

Basal testing is usually done over a period of 3 to 4 days, and it can be kind of complex avoiding the various variables that could skew results.

If your blood sugars are truly all over the place or you’ve just started a new insulin regimen (like switching from Lantus to Tresiba, or from injections to a pump), working with your healthcare team on basal insulin testing is the wisest plan of attack.

But if you’re not in dire straits and would rather not do basal testing too frequently, sometimes a little tweaking on your own is an easier approach with quicker results.

Either way, the biggest takeaway is that even a small adjustment in your background insulin doses can make it so much easier to stay in your goal blood sugar range for most of the day.

In case you haven’t picked up on the theme here yet: A tiny adjustment of just 1 or 2 units can have a big impact.

If you’ve been frustrated with highs, roller-coaster glucose levels, and an inability to get your A1C down a notch, it’s likely time to do some fine-tuning — with or without the help of your healthcare team.