• Steve Mann

Fine Tuning for Improved Management and Lower A1C's

I notice many "courses" being offered to lower your A1C in a matter of weeks. But this is not a matter of focusing on your A1C...it's a matter of fine-tuning your settings. No matter how you take your insulin, this fine-tuning is the key to improving the management of your diabetes... and eventually achieve better A1Cs. Fine-tuning must be embraced as a desired and sustainable change in behavior.

Essentially, it comes down to a few areas:

  1. Test your basals

  2. Test your carb ratios

  3. Test insulin sensitivities

That's it! That's all they wrote! Does this seem hard? Once you get the hang of it, it's not.

Before we start, however, here is the usual disclaimer - I am neither your doctor nor anyone else's doctor. My words are no substitute for conversations with your healthcare team.

The basic objectives of tuning include:

  • Basal rates should keep your BGs steady in the absence of other influences (including food, medications, etc).

  • Boluses should return your BGs to target after a meal.

  • ISF (Insulin Sensitivity Factor) should be the amount one unit of insulin drops your BGs without other influences.

  • Carb ratios should bring your BGs close to your pre-meal level.

Now it is possible that the wrong setting in one area looks like the right setting if another balances this error. The problem is they won't balance in all situations. For example, if your basals are too low, they can be offset by the regular eating of meals with too strong of a carb ratio. But if you stop eating, you'll start to go high, because the extra insulin from the meal boluses won't help with insufficient basals.

One of the keys to good control is regularly testing these settings and adjusting as necessary. Let's look at each in more detail.

[Pumpers: we're not going to pay that much attention to DIA (Duration of Insulin Action). In traditional pump use, DIA is only used to calculate the remaining IOB at any given time after a bolus. That’s it].

Fine tuning your basal rates

Testing basals is simple and doesn’t require days of fasting. Instead, look for natural opportunities.

Don’t eat food, don’t do crazy exercise, don’t sit in a hot tub.

Just have a relaxing average time and see if your basals can hold you roughly steady. It doesn't matter whether you're at your target BG or not, the idea is simply not to have bolus insulin on board to cover food or a correction dose and see what happens. Typically, you need two hours without the influence of food or correction bolus to accurately test and tune a basal rate. If you pump and have multiple basal rates, you would test each of them.

Insulin sensitivity factor

Your Insulin Sensitivity Factor (ISF) is used to figure out how much bolus insulin is needed to get to your target.


  1. Take one or two glucose tablets.

  2. Wait for your BGs to be steady at the higher BG.

  3. Give a safe correction bolus that you believe will bring your sugars close to the target.

  4. Watch the resulting BG drop over the next 2-3 hours.

  5. You should observe your blood sugars come to a steady level again.

Now -- two key questions.

  1. How much did the BG drop?

  2. And, how many units of insulin did you use?

Divide the two numbers and you have your ISF.

For example, if your BG dropped 15 mg/dl with half a unit of insulin, your ISF is approximately 30 mg/dl/unit.

Applying this knowledge.

  1. You tested your ISV and it's 30 mg/dl/unit

  2. Your typical target BG is 100 mg/dl

  3. Current BG is 160 mg/dl

  4. You would take 2 units of insulin to get to target

Carb Ratios

Okay! You've nailed your basal rates. You're comfortable with your ISF. Now it is time to test your carb ratios (CR). Your CR determines how much insulin you need for any amount of carbohydrates. It can vary depending on the time of the day (for example, it is not unusual to require more insulin in the morning for the same amount of carbohydrates as in the rest of the day).

An acceptable carb ratio will bring your BGs back to the starting point of the meal within three hours.

If you have a poor carbohydrate ratio, you will be higher or lower than the starting point of the meal.

Your doctor often initially sets your carb ratio, but should be tested regularly due to YDWV (Your Diabetes Will Vary). And since you know your diabetes better than anyone else, you should choose the times to do this. You don't have to wait for your Endo to suggest it.

A carb ratio of 1:10 means that that 1 unit of rapid-acting insulin will cover 10 grams of carbs.

The higher the ratio, the less insulin to cover your carbs.

If your carb ratio is 1:10 and you eat 30 grams of carbs, you need 3 units of rapid acting insulin to cover the meal (30 divided by 10). However, if your carbohydrate ratio is 1:15 you will need 2 units of rapid insulin (30 divided by 15).

When you set your insulin peak with your meal, a precise carb count combined with an accurate carb ratio means your blood sugar should remain within your desired range.


I suggest following the 4 steps below for 3-5 days if you're a data nerd - collect more, but 3 days can give you enough data to cover various scenarios and make a better informed decision about your ratio.

  1. Focus on one meal at a time (breakfast, for example). Try to enjoy the meal roughly the same time each day, and eat the same foods and quantities for the data collection period. Normally I choose a few pieces of low fiber bread because it is easy to ensure your carb count is accurate.

  2. Try not to do anything that significantly affects blood sugar before or after the meal (like running).

  3. Stay on top of your blood sugars.

  4. Measure your blood sugar before the meal.

  5. Measure your blood sugar after the meal -- at 2, 3 and 4 hours post the meal.

  6. You will then see how close you are to your target BG within 3 hours of meal.

Evaluation and change

BG in range before the meal, but doesn't come down to target within three hours.

If your BG is not close to the target within three hours after a meal, you can experiment with ratios reduced by 1. For example, if you start with a ratio of 1: 10 (1 unit covers 10g of carbohydrate), you can try 1:9 and then 1:8 to determine which ratio works best for you.

Remember, the lower the carb ratio, the more insulin you need per gram of carbs.

Blood sugar in-range before the meal, but low within three hours

If your blood sugar is lower than your target range within three hours after a meal, your carb ratio is likely too low (you are taking too much insulin). You can test incrementing your ratios by 1. If you are starting at 1:10, go to 1:11 or 1:12 and test your CR again.

My CR is 1:7 - for 10g of carb, I need 1.4 units of insulin.

For female T1Ds

As you already know, hormones can be a huge variable in blood sugar management, so you have to test your ratios in that context. Your basal rates may need to be modified to address hormonal fluctuations.


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