Optimizing glycemic control: can insulin dependent diabetic patients rely on their perception of blood glucose fluctuations in order to make therapeutic decisions?

30 insulin dependent diabetic (IDD) patients without clinically evident autonomic neuropathy were asked on 128 occasions to estimate quantitatively what they believed their capillary blood glucose (CBG) to be (predicted blood glucose--PBG) immediately before an actual CBG measurement was performed (real blood glucose--RBG). A statistically significant correlation was found between the pooled RBG's and PBG's of our patient population (r = 0.57, p less than 0.001). However, there was a notable skewing of the RBG/PBG curve, evidencing a tendency of our patients' predictions to be closer to normality. This is further documented by the fact that the mean M value of the RBG's of each of the 11 patients with more than 6 predictions was significantly greater than the mean M value of the corresponding PBG's. Within the ranges of hypoglycemia (RBG less than or equal to 3.3 mmol/l) and of normoglycemia (3.4-7.8 mmol/l) there was no correlation between RBG's and PBG's. With RBG's greater than or equal to 7.8 mmol/l the correlation was statistically significant (r = 0.41, p less than 0.01). When the pooled predictions were analyzed according to qualitative accuracy for different ranges of RBG the following trend emerges: for RBG's less than or equal to 3.3 mmol/l (60 mg%), 2/11 predictions were accurate (18%), for RBG's greater than or equal to 12.3 mmol/l (221 mg%), 30/37 (81%) and for RBG's between 3.4 and 12.2 mmol/l (61-220 mg%), 44/80 (55%). In conclusion, our patients as a whole showed an ability to discriminate between high, normal and low levels of blood glucose, albeit with a strong bias to predict values closer to the normal range.(ABSTRACT TRUNCATED AT 250 WORDS)