Abstract

OBJECTIVE: We propose a novel algorithm to adjust prandial insulin dose using sparse blood glucose measurements. The dose is adjusted based on a performance measure for the same meal on the previous day. We determine the best performance measure and tune the algorithm to match the recommendations of experienced physicians.

RESEARCH DESIGN AND METHODS: Eleven subjects with type 1 diabetes mellitus, using CSII, were recruited (7F/4M, age 21--65 years, glycated hemoglobin of 7.1±1.3%). Basal insulin infusion rates were optimized. Target carbohydrate content for the lunch meal was calculated based on a weight maintenance diet. Over a period of 2-4 days subjects were asked to measure their blood glucose according to the algorithm's protocol. Starting with their usual insulin to carbohydrate ratio, the insulin bolus dose was titrated downward until postprandial glucose levels were high (180--250 mg/dL, 10--14 mmol/L). Subsequently, physicians made insulin bolus recommendations in order to normalize postprandial glucose concentrations. Graphical methods were then used to determine the most appropriate performance measure for the algorithm to match the physician's decisions. For the best performance measure, the gain of the controller was determined as to best match the dose recommendations of the physicians.

RESULTS: The correlation between the clinically determined dose adjustments and those of the algorithm is.

CONCLUSIONS: We have shown how engineering methods can be melded with medical expertise to develop and refine a dosing algorithm. This algorithm has the potential of drastically simplifying the determination of correct insulin to carbohydrate ratios.