Assessment of experts' approach to insulin therapy and development of a simulator for diabetes insulin adjustment.
OBJECTIVE: To develop a computer program (Macintosh) to predict changes in blood glucose after changes in insulin dose, timing, and regimen. RESEARCH DESIGN AND METHODS: We established program parameters (apparent insulin action profiles; different for insulin-dependent and non-insulin-dependent diabetes mellitus) to match predictions by five diabetes specialists at our hospital of blood glucose changes after insulin-dose adjustment in 22 hypothetical patient cases. We compared the action profiles, which represent the blood glucose changes predicted by the experts with glucose-clamp studies of insulin action. We tested the program's performance in 22 different hypothetical cases against the responses of 15 specialists from outside our hospital. RESULTS: The specialists, when predicting effects of insulin dose adjustment, integrate numerous processes (insulin action, diet, sequential blood glucose interactions). They could not specify algorithms for determining these individual factors, but they could easily predict the overall effect in the context of patient cases. The computer program's insulin-action profiles simulate this "composite" approach. The developed program incorporates multiple insulin regimens, which may be changed during the stimulation, and adjusts predicted responses according to the patient's estimated sensitivity to insulin. Its predicted change in 172 blood glucose levels (22 cases) correlated well with the corresponding means of the outside specialists (r = 0.83, P = 0.0001). Comparing this correlation with that of individual specialists ranked the program third. CONCLUSIONS: A computer program can simulate specialists' "composite" approach (not based purely on conscious application of physiological data) to insulin adjustment.