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By kparun
#37
Dear All,

Can anyone share an authentic information about insulin dose calculation based on blood sugar levels. It would be great if given with references.

Dr. Arun KP
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By Admin
#52
Dear sir,
Adjusting insulin dose based on blood sugar
It mainly depends on 3 factors
 Insulin type
 Insulin to carbohydrate ratio
 Insulin sensitivity factor ( correction factor)

Insulin type
Regular, NPH (long acting), NHA (fast acting), LANTUS (long acting)
We can go with combinations of (NHA+ NPH), (LANTUS+ NHA) or insulin pump therapy (fast acting)
Out of total daily dose of insulin, 40-50% is required to maintain overnight insulin levels between meals or during fasting which is called basal insulin. Remaining 50-60% is required to cover carbohydrate and to reduce high blood sugar (correction factor) which is called bolus insulin. Fast acting insulin comes under bolus and long acting we can add in basal.

Insulin to carbohydrate ratio
To calculate insulin coverage for each gram of carbohydrate we need to find out the TOTAL DAILY INSULIN DOSE (TDI)
TOTAL DAILY INSULIN DOSE= Weight in Pounds ÷ 4 or 0.55 X Total Weight in Kilograms
To fix up basal insulin dose it is 40-50% of TOTAL DAILY INSULIN DOSE
Carbohydrate coverage ratio= 500 ÷ TDI
For example: if TDI IS 20 Units for a person then 500/20=25, this indicates 1unit of insulin covers 25g of carbohydrates (CHO)
As individual insulin sensitivity varies, insulin-to-carbohydrate ratio at different meal times should be adjusted.

Insulin sensitivity factor (correction factor)
Correction Factor = 1800 ÷ TDI
For example: if TDI IS 20 Units for a person then 1800/20=90, this indicates 1unit of insulin drops blood sugar by 90 points (mg/dl)

Combining all the above and adjusting a dose

If a person blood sugar is 240mg/dl before lunch but normal blood sugar target before meal should be 120mg/dl
High blood sugar correction dose = Difference between actual blood sugar and target blood sugar* ÷ correction factor.
High blood sugar correction dose =240-120
So 120 blood sugar points should be reduced in this person and if TDI is 30 units in this person then
Correction Factor = 1800 ÷ 30 i.e. 1unit of insulin reduces 60mg/dl of blood sugar.
As 120 points should be reduced in this patient we need to give 2units of insulin to bring the target level.
If this same person going to have 60g of CHO in a meal then
CHO insulin dose = Total grams of CHO in the meal ÷ grams of CHO disposed by 1 unit of insulin
Grams of CHO disposed by 1 unit of insulin =500/30 i.e. each unit of insulin covers 16.6g of carbohydrates
So, CHO insulin dose= 60/16.6 i.e. 3.6 units of insulin is required to cover 60g of CHO in his meal

Finally, to fix his mealtime insulin dose,
Total Meal Insulin Dose = CHO Insulin Dose + High Blood Sugar Correction Dose
Total Meal Insulin Dose=3.6+2 =5.6
Nearly 6 units of insulin meal dose is required to maintain his target levels

References:
http://www.welcometotype1.com/en-us/#chalk-talks
http://dtc.ucsf.edu/types-of-diabetes/t ... ulin-dose/
http://www.ucdenver.edu/academics/colle ... s/ud21.pdf

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