Self-monitoring of blood glucose and insulin dose alteration in type 1 diabetes mellitus.

The purpose of this study was to evaluate the relationship between proper use of self-monitoring of blood glucose (SMBG) including knowledge and application of specific algorithms and metabolic control in a group of randomly selected insulin-dependent diabetic patients. We studied 80 patients responding to the following criteria: intensive conventional insulin therapy and SMBG for at least 6 months using a reflectance meter, and previous 5-day hospital education period. The practical knowledge of the guidelines was evaluated by a questionnaire simulating 8 metabolic situations. A computer analysis of the SMBG data for the 3 months preceding the study allowed us to evaluate patient compliance with SMBG (number of blood glucose determinations) and patients' application of the guidelines (percentage of insulin doses modified according to the guidelines). Fifty-nine patients (79%) were compliant with SMBG and had better metabolic control than the non-compliers (HbA1c: 6.7 +/- 1.1% vs. 7.5 +/- 1.9, P < 0.05). Twenty-eight out of the 59 compliant subjects had good knowledge of the guidelines but without patent improvement of glycemic control. Seventeen of these 28 correctly used the algorithms to modify insulin dosage; their HbA1c levels were lower than those of the 11 patients who did not use the algorithms (6.1 +/- 0.9 vs. 7.1 +/- 0.9%, P < 0.05). The percentage of insulin dose modification consistent with the guidelines and the level of HbA1c was negatively correlated in the good-knowledge group. The conclusion is that good metabolic control is linked not only with the degree of knowledge but also with the application of this knowledge.