I was diagnosed type 1 (LADA) this past September at 40 years old. I have read that typically your total daily dose of insulin is divided roughly 50/50 into basal and bolus. When I first started on insulin I was taking 10 units per night of Lantus, which I have gotten down to just 5 units per night (waking up around 100). My boluses, though, end up around 9-10 units of insulin per day. That makes my proportion more like 33/66 instead of 50/50. Is that normal for LADA? I had a c-peptide test done at diagnosis but it was not done fasting. My result was 0.8, which was the bottom of the lab’s range of normal.
Just a couple of days ago I was taking 6U of Lantus per night, which I reduced to 5 due to recurring lows. Last night my Dexcom was hollering and I tested at 78. I’m almost wondering if I should reduce by another unit, but I’m weirded out by the fact that my proportions already seem so off of normal. Any input?
My experience is almost identical. I went 18 months with zero basal and an I:C ratio between 1:20 and 1:15. Almost four years in, I am currently at 6 units basal and an I:C ratio of between 1:8 and 1:15, depending upon time of day. A few months ago, I had a lingering cold and my basal was up to 10 units per day, but it's drifted back down....for now. I think the slow onset T1 presents in varying ways.
I am a long-term T1D/LADA, 31 years. I think that the basal/bolus 50%/50% is not useful as a target. I vary my daily basal/bolus split from 40/60 to 60/40. My 14-day average right now is 47/53 basal/bolus.
My basal insulin doesn't change by much but can fluctuate up to 1 unit each week. I adjust basal rates about twice a week. My philosophy is you need the insulin you need. My bolus insulin is driven by what I eat. On days I eat less, my bolus insulin is less. An artificial ideal is just that. I would pay it no mind!
The important thing is that you can maintain a high percentage of your time in range. A CGM is the easiest way to get this info but if you provide enough well-timed fingersticks then you can also approximate this number.
I've seen this issue raised by others online and I don't get the rationale. Take the insulin you need to control BG levels.
Now, having said that, I know I have been heavy handed with insulin in the past and aggressively added copious amounts of insulin and then "ate to my insulin." That is definitely not a good way to control BGs. I found that I caused many lows myself by overdosing, only to rebound later and chase with more insulin. That leads to a self-perpetuating and exhausting roller coaster that doesn't want to end. It also adds to weight gain and insulin resistance!
In a discussion a couple weeks ago, Acidrock linked to this article by Dr. Stephen Ponder on the basal/bolus breakdown. He also disagrees with 50/50 as a target:
I have had the same experiences. 50/50 has never worked for me. It was a good starting point when first trying to figure everything out but as time goes on - there are many of us who realize that we do better on different percentages. I have always been on a small amount of basal and need a lot more insulin - about 60 to 70% as my boluses.
This fixed relation of 50/50 comes from the old days. Back then people had fixed eating patterns: they ate a fixed amount of carbs at fixed times. Their insulin dosage was fixed and their basal was fixed.
Today we estimate the carbs. For this amount we will inject the amount of insulin according to the carbs covered per unit for this hour of the day. As a result we often eat to the same schedule but with different amounts of carbs. Thus the relation of bolus to basal is constantly changing every day. I have days ranging from 58:42% to 72:28% - all depending on my flexible carb intake.
The relation itself is not important in my opinion. Your basal should cover your basal needs (the glucose coming from the liver). It is really important to find the right dosage for the basal. Otherwise you would cover some of your basal needs with your bolus insulin. For example you would assume one unit of bolus will cover 9g but with the correct basal dosage and coverage it would have been 12g. These errors will scale with the amount of carbs. This could lead to lows with higher amounts of carbs and vice versa. Basal rate testing is one way to determine the correct (better fitting) basal dosage for your average activity level.
Thank you all for the input! I guess I had it in my head that 50/50 was the "goal", rather than just being what some people observed. Shadow, I had actually read that post by Dr. Ponder, I don't know why I had forgotten it! I also found the study he referred to, indicating that under controlled conditions, at least, the split was more like 30/70 basal/bolus.
I'll just let the meter's number guide me, then, instead of worrying about the proportion.
50/50 is a "rule of thumb", not a medical standard for what is "normal". It's just approximately how TDD works out for full-on T1's (and presumably non-diabetics' endogenous production).
This approximation is completely invalid for LADA and T2. For such diabetics, basal/bolus ratios will be very individualized, all over the map, depending on how much beta cell function/capacity they have, insulin resistance, etc.
I am mainly basal and next to no bolus. I eat low carb, so this helps with the low bolus.
Typically my basal is about 25 units / day and my bolus is < 5 u day. So my ratio of basal to bolus is > 5:1.
If I ate a lot more carbs I would need more bolus, but not going to be anywhere near 50:50, and certainly not worth the inevitable lows that would happen with that much bolus.
The 50/50 ratio is based on a nearly complete insulin deficiency and a high carb diet. If you still make some insulin you may make enough to sustain your natural fasting blood sugars but not enough to deal with meals, hence your ratio may drop explaining your 33/66 needs. If you eat very low carb and have little insulin production you may use little bolus to deal with meals due to the low carb and have more like a 30/70 or even 20/80. Mine is more generally 30/70, but I don't worry about the ratio, I worry more about TDD.
This is a GREAT discussion, as I am struggling with my blood sugars and basal/ bolus rates. My sugars have been crazy. I am not happy. My Insulin to Carb ratio has only been adjusted one time by my end's in 7 years. Before I was a full-on T1D they tried me Byeta pens and then regular Homolog pens ( I think) that was nuts. I love me Medtronic pump and can't imagine trying to keep up with 2 kinds of Insulin or needle shots every day.
I re-adjusted my basal rates last night ( after feasting on ...dare I say...at least 3 cups of full fat Rum Raisin ice cream. I bloused well, but everyone knows, that dang Ice cream (or Pizza) will screw your BG's up for hours. My sensor drove me nuts all night. Up and down . I hope I learned my lesson. I do set my pump for different basal rates throughout the day. I was told that I have Dawn Phenomenon, so that has to be adjusted for. And then my Bg's usually start to go up later in the afternoon, and so I get more basal then too.
Thanks for bringing this up, Elena. These personal stories are very informative.
40/60 is good for me...50/50 was just a number they pulled out of thin air. The clinical rules needed a starting point. I only used regular insulin for the first 15 years of my diabetes career...and today it's all U100 insulin when I used a basal insulin it still lowered my BG the same as my fast acting does per unit...it just takes a lot longer to get the job done.
I'm not sure where endos got the idea that bolus and basal need to have some particular range of "proportion" or ratio. You need what you need. I follow a sort of low-carb diet, but not extreme. Every time they download my pump they act concerned that I'm not in the 50/50 range, more like 35/65. Who cares? My basals work fine, and I have checked them recently. And while my bolus needs change from morning to night, they are mostly working too. Just seems like a lame thing for them to care about.
