Background: CGM is used to monitor/assess diet related glucose excursions and suggest treatment changes in types 1 and 2 diabetes. Two CGM data derived parameters, timed glucose clearance (GLCL(T,I) and timed insulin sensitivity index Si(T,I) are developed to quantify treatmentresponses to food, medication, and activity.

Method: Glucose Clearance (GLCL) = Interstitial fluid volume (Vd)/time of the (t1) rise and return to baseline (t2) of the diet related glucose concentration curve. GLCL(T,I) indicates the time = T between insulin administration (t0) to the initial glucose concentration rise from baseline (t1). I = insulin dose. The Si(T,I) = GLCL(T,I)/rapid acting insulin dose administered. Vd = 0.15 * kg body weight * 10 expressed as deciliters (dL).

Result: Example #1 - Two similar breakfasts: oatmeal (1 cup), 6 strawberries, ½ cup blueberries and ½ cup cottage cheese (46 g CHO) ingested on two different occasions. Vd = 116 dL. Breakfast (A): T = 0 minutes, glucose curve duration = 180 min, I = 13 units, GLCL(0,13) = 64.4 ml/min and SI(0,13) = 5.0 mL/(min*unit). Breakfast (B): T = 45 min; curve duration = 90/min; I = 12 units, GLCL(45,12) = 129 mL/minute and SI(45,12) = 10.8 mL/(minute*unit).

Example #2 - Lunch: madras lentils and hot dog. T = 0 minutes, I = 14 units. Glucose curve duration = 270 min. GLCL(T,I) = 43 mL/min; Si(T,I) = 3.07 mL/(min*unit).

Conclusion: Two quantitative parameters assessed similar meals and showed marked differences in duration and height of the glucose concentration curves. They illustrate the importance of insulin injection timing and dosing. The calculations are also applied to a meal without carbohydrate (CHO) counting and can be compared with a comparable subsequent meal. The calculations do not depend on CHO counting and can be applied to Identical mixed meals. Straightforward calculations are applied retrospectively to CGM generated data beyond current more qualitative CGM data evaluations.


J.S. Melish: None.

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