Are Glucose Readings Sufficient to Adjust Insulin Dosage? Eran Bashan, Ph.D., 1 William H. Herman, M.D., M.P.H., 2 and Israel Hodish, M.D., Ph.D. 1,2 Abstract Aims/hypothesis: Insulin therapy is effective predominantly when dosage is frequently adjusted. However, a controversy surrounds the pertinent clinical parameters required to make effective and safe frequent dosage adjustments. We hypothesize that glucose readings are sufficient to adjust insulin dosage provided that dosage is adjusted every 1–4 weeks. Methods: To test the hypothesis, we generated several algorithms implemented in software to process glucose readings and recommend insulin dosage adjustments. A post hoc analysis was made on 630 log sheets (2,520 insulin dosage adjustments) from 26 older adults with suboptimally controlled type 2 diabetes. The subjects were followed for a year and treated with intensive insulin therapy that was titrated every 1–4 weeks by a trained study team. More than 88% of subjects attained the treatment goal (hemoglobin A1c <7%) without excessive hypo- glycemia. Glucose readings from each log sheet were used as an input to the software, and its recommendations for insulin dosage adjustments were compared to the original ones made by the study team. While the study team could have been exposed to multiple clinical parameters, the software relied solely on glucose readings. Results: The software recommendations for dosage adjustments were clinically equivalent to the original study team’s recommendations in more than 95% of the cases, unrelated to patients’ insulin sensitivity. The remaining 4.4% (n ¼ 111) were thoroughly examined, yet we did not find any recommendations suggested by the software to be unsafe or unreasonable. Conclusions/Interpretation: Glucose readings are sufficient to effectively adjust insulin dosage provided that adjustments are made every 1–4 weeks. Therefore, dedicated software can help adjusting insulin dosage be- tween clinic visits. Introduction I nsulin is the only antidiabetes agent lacking a thera- peutic window. In other words, most insulin-treated patients can achieve satisfactory glycemic control provided that appropriate formulations and adequate dosage are pre- scribed. Yet, almost two-thirds of insulin-treated diabetes patients in the United States fail to reach the therapy goal (hemoglobin A1c [A1C] <7%), 1,2 although compliance to an- tidiabetes medications is generally considered adequate in about three-fourths of the cases. 3,4 Most insulin users have type 2 diabetes; some use partial insulin therapy (premixed, biphasic, or long-acting insulin), and some use intensive in- sulin therapy (basal/bolus). Only clinical trials that reinforce a policy of insulin dosage adjustments every 1–4 weeks (cumulatively >15,000 patient-years) for either partial 5–10 or intensive insulin therapy 11–13 achieved treatment goals (A1C <7%) among 40% and 80% of the subjects, respectively. Al- though this finding is hard to separate from the Hawthorne effect, when trials have ended and frequent insulin dos- age adjustment strategy was replaced with infrequent con- servative care predominantly during clinic appointments, patients’ A1C was unfavorable merely a year after study termination. 13,14 The nature of this paradox likely ensues from patients’ metabolic behavior. Because of variability within each patient (Fig. 1), insulin requirements significantly fluctuate over time and thus cannot be met by infrequent dosage adjustments during clinic visits (typically once every 3–6 months). Most clinicians agree that insulin dosage should be titrated/ adjusted far more frequently than during routine clinic visits. However, the clinical parameters as well as the frequency required to make effective frequent dosage adjustments are still controversial. Insulin dosage should not be confused with insulin doses that for some regimens may depend on pre- prandial glucose reading (sliding scales or correction factors) 1 Hygieia, Inc., Ann Arbor, Michigan. 2 Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan. DIABETES TECHNOLOGY & THERAPEUTICS Volume 13, Number 1, 2011 ª Mary Ann Liebert, Inc. DOI: 10.1089/dia.2010.0112 85