In the recent consensus statement by Kitabchi et al. (1) is a serious contradiction. In diagnosis, the authors write that “the initial laboratory evaluation of patients with suspected [diabetic keotacidosis] … should include determination of … osmolality … Studies on serum osmolality and mental alteration have established a positive linear relationship between osmolality and mental obtundation (14). The occurrence of stupor or coma in diabetic patients in the absence of definitive elevation of effective osmolality (320 mOsm/kg) demands immediate consideration of other causes of mental status change.” In sharp contrast to this statement is Table 1 of the consensus statement, where the effective serum osmolality is in all three categories of mental status, “Alert,” “Alert/drowsy,” and “Stupor/coma,” the same: “variable.” On the other hand, the mental status “Alert” has arterial pH of 7.25 to 7.30, “Alert/drowsy” 7.00 to <7.25, and “Stupor/coma” <7.00. Thus, the impression from this Table 1 is that there is a correlation between decreasing level of consciousness and decrease of arterial blood pH (and not with increase of serum osmolality).
The observations of Edge et al. (2) in a recent study are the same as the data in Table 1 of the study by Kitabchi et al. (1) regarding a correlation between decreasing blood pH and decreasing level of consciousness and absence of correlation between increasing osmolality and decreasing level of consciousness. The correlation between blood pH and level of consciousness is not only statistical but also causal. Activity of the glycolytic enzyme phosphofructokinase is decreasing with decreasing pH (3,4), and, thus, utilization of glucose is impaired (also in brain cells [5]). Without normal utilization of glucose, the function of brain cells is impossible.
