Determining Basal, Carb Ratio and Sensitivity (A Personal Experience)

I recently received a kidney transplant and as a result my basals, carb ratios and sensitivities changed and needed to be redetermined. I have had type 1 diabetes for 52 years, since I was 15. It was a very frustrating experience to figure out new settings but I finally got through it and had some success. I have a Medtronic 723 pump and a Dexcom G5 CGM. I use Dexcom Clarity software and Medtronics Carelink software to help me view reports. Software is not required to determine new settings but they can be helpful.
I am going to detail how I went about redetermining my basals, carb ratios and sensitivities which worked for me. I realize diabetes is different for everyone so hopefully some will find this helpful and others will not. Hopefully it will generate a discussion which is always a good thing. Most experienced diabetics will find this too simple. My target audience is those that have not tried to determine these settings themselves.
Your liver produces sugar to give you energy and your pancreas produces insulin to keep your sugar levels within a narrow but appropriate range. They work in tandem and provide non-diabetics with the perfect system.
Unfortunately, diabetics produce a limited amount or no insulin and thus we need manufactured insulin to keep sugars produced from the liver and from food from rising too high. I want to emphasize that we have no or a very limited control over when or how much sugar the liver produces. Thus, when we think we are doing everything right managing our diabetes, we can still have unexplained high or low BGs for no reason except for the fact that the liver produced sugar levels we did not anticipate.
I have stopped trying to figure out why we have unexplained high and low BGs (believe me, I have tried) and now realize we have no control over the liver and can only hope that it produces sugar systematically.
The liver, food, exercise, time of day and other factors all affect sugar levels. As a result, we have come up with basal rates, carb ratios and sensitivities which we assume are approximations of the pancreas’s reaction to the liver’s systematic production of sugar and the consummation of food.
Basal Rates
Basal rates should keep your BG even as long as there are no other sources presently affecting BG such as having recently consumed food or drink (which raises BG), recently taken a bolus (which lowers BG), exercised (which lowers BG) or time of day (which could raise or lower BG). I believe boluses reduces my BG for 4 hours. Thus, after a meal at 12:000 PM, I would wait until 4:00 PM and then start watching my BG until the next meal or bolus. You can try to be as precise as possible and use real blood to measure BG or if you have a CGM you can just track the readings and assume they are correct or the trend is correct.
Next post will be the actual determinations and calculations.


Thinking through how your glucose metabolism works and then writing about it is a powerful way to cement your diabetes knowledge.

There seems to be no end to what one needs to know about diabetes in order to live well with it. Learning a little each day is the antidote for that.

I look forward to reading your next post with how you do your calculations. Good luck!

Apparently very little interest in the post so I may not finish it.

Have seen you several times in different topics. Good luck as well.

I wouldn’t jump to any conclusions. It’s hard for me to predict interest in any topic that I post. I’m often surprised at the level of interest once some time has passed.

The beauty of this type of message environment is that people will continue to read what you’ve written long after you think few care. I see writing as a great way to think through an idea. I’m still interested in what you’ve learned if you want to share.


When I read your post, I was surprised to read it was about basal and carb ratios, after sharing about your kidney transplant. It would be very interesting to hear more about that, and curious if you still require insulin basal, bolus, after new kidney. How long did you have to wait. What were the symptoms. We don’t have many post related to that

Typically people post specific issues with basal, bolus calculations, or refer to their doctors or book’s that were mentioned. It is an individual thing.

1 Like

Some of us read much, but comment little. I will likely continue reading your story, though I may not feel a need to reply. I do appreciate the offering.


This is the second part of my post on 9/1/18, “Determining Basal Rates, Carb Ratios and Sensitivities (A Personal Experience)”
This part will demonstrate how I determine adjustments to basal rates. First, I have to explain some concepts as without these concepts you might make some wrong inferences.
An important concept is that basal rates are similar to bolus rates in that they are both delivered at a point in time (although basals are delivered in small increments over a period of time) and they affect your BG over the duration of insulin delivered, assume 4 hours. This is easy to understand if you just consider that insulin is insulin whether it is delivered as a basal or bolus and it must have the same duration absorption.
Thus, the concept of averaging comes into play. Assume you had basal rates of 1.0 from 12AM-8AM and 1.2 from 8AM-2PM. Although you are beginning to deliver your basal at a rate of 1.2 at 8AM your BG readings at 8AM are affected by the basal drops delivered over the past four hours. You will not see the full affect of the 1.2 basal rate until 12PM. Thus, the basal change will not fully impact your BG readings immediately but will begin to affect them.
The second reason this is important is because any change you make to a basal rate to one period will also affect another period. For example, if you changed your basal rate from 1.0 to .9 from 12AM-8AM, this change will affect the next period. Since you are delivering at a new rate until 8AM, basal drops delivered at 7AM, for example, will affect your readings for the period 7AM-11AM. Always be conscious that a change in basal rates for one period will have an effect on another period.
As stated previously, you should test to see if your basal rate is accurate or needs to be changed only when there are no other factors present which could affect you BG. Basal rates should keep your BG steady as long as there are no other sources presently affecting BG such as having recently consumed food or drink (which raises BG), recently taken a bolus (which lowers BG), exercised (which lowers BG) or time of day (which could raise or lower BG).
I tested my basal rate last night from 11:00PM-11:35PM. Food was gone (I ate at 7:15PM), meal and correction boluses were gone (delivered at 6:45PM), I had not exercised and I was not sick. My basal from 11:00PM to 11:30PM was .9. Below were my BG readings (per my Dexcom):
1100 156
1105 157
1110 158
1115 159
1120 161
1125 162
1130 162

My conclusion was that my basal rate was too low as evidenced by the fact that absent all other factors affecting BG (except unsystematic sugar from your liver) my BG was rising at a steady rate. Thus, I decided to increase my basal rate tomorrow.
My insulin sensitivity is 70 meaning 1 unit of insulin should drop my BG 70 points per hour. Thus .1 units should drop my BG 7 points per hour. In fact, based on this limited sample, my BG dropped 6 points in ½ hour or 12 points in an hour and thus a calculated change in basal approximates .2U per hour. Rather than increase my basal from .9 to 1.1, I decided to increase it slowly and test it tomorrow. Thus, I decided to increase my basal from .9 to 1.0.
As a matter of practice, I would suggest you use a larger sample size than ½ hr. I limited myself to ½ hr so I could go to bed. Secondly, you should probably test this for two or three days and see if you get the same result before making a change. I decided to make the change but then to test the basal tomorrow to confirm that change was appropriate.
You can test basals for any period once you determine that all other factors (food, boluses, exercise, sickness) affecting BG are eliminated. Once again, I strongly suggest you use a larger sample size than I did in this example.
I should also note that if you test your basal for an hour then you are concluding that is the correct basal rate for only that hour. A month from now you may test the basal for the same time period and it may be different. That is why it is so difficult to get basals correct and to try to maintain correct basals.
As mentioned in many articles and books, you should get basals correct or close to correct before trying to determine either carb ratios or sensitivities. It could take months and may require some fasting. Although not difficult, you should also reconfirm your findings. Consequently, you have both many time periods to confirm and you should actually confirm your findings at least two times.
Tomorrow I will finish with Carb Ratios and Sensitivity. Anything written here are my beliefs after having diabetes for 50 years and after spending an inordinate amount of time lately coming up with changes to my own settings which were required as a result of a kidney transplant. I realize there are many different opinions out there.

Thanks I will post something on my transplant one day. I did not have a combo kidney/pancreas transplant so I am still a type 1 diabetic but need even more insulin now as the new kidney tries to rid the blood of objects like manufactured insulin,

1 Like

Sorry about that, I made wrong conclusion, though you stated it clearly. My dad is not diabetic, but very bad kidney function at this point, so always interested in kidney related stories.

Simple method for testing nasal rates is to skip a meal. Your blood sugar should remain constant after previous meal spike and insulin are cleared out. You can do this for each meal, no more than one per day. You might have to repeat skipping a meal if you made basal adjustments. Also, you need to be eating fairly consistent carbs per day. If you eat execeasive carbs, your liver will store these and you may have elevated BG for a day or two as that excess is releasesd.

1 Like