In describing overbasalization in a previous issue of Clinical Diabetes, Stewart-Lynch et al. (1) promulgated its mistaken definition (>0.5 units/kg/day) by the American Diabetes Association (ADA). This definition is based on 374 individuals with type 2 diabetes starting U-100 glargine insulin in three Sanofi phase 3 trials in which 46% required >0.5 units/kg/day. Unfortunately, the fasting plasma glucose (FPG) and A1C changes were normalized to 0.1 units/kg/day instead of presenting the usual absolute changes (2).
This erroneous outcome guarantees that higher doses of insulin will yield lower responses. Consider that two people receiving 0.3 and 0.5 units/kg/day of basal insulin, respectively, both experience a 50 mg/dL decrease in FPG. Per 0.1 units/kg/day, the first person’s decrease would be 167 mg/dL, whereas the second person’s decrease would be 100 mg/dL—40% lower. The same scenario would apply to A1C changes.
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