Reliability of Pre- and Post-breakfast Blood Glucose as an Index of Glucose Control in Elderly Diabetics

Abstract

The aim of our study was to define the reliability of pre-breakfast and post-breakfast blood glucose as an index of glucose control in elderly diabetics. We have, therefore, examined the correlation between plasma glucose levels and HbA₁ values in diabetics who showed relatively stable in glucose control. The rsults were as follows: 1) Both the pre-breakfast plasma glucose (FPG) and 2-3h post-breakfast plasma glucose (PPG) values showed a strong positive correlatin with HbA₁ and HbA_1C values determined at 4, 8 and 12 weeks after testing in both diet-treated and drug-treated groups. As a whole, the best correlations were found 4 weeks after testing. 2) The correlation coefficient between HbA₁ and PPG 4 weeks after testing in both diet-treated and drug-treated elderly (60 years and over) groups was significantly lower than its correlations with FPG and PPG in the adult (59 years and under) groups and FPG in the elderly groups. 3) In both diet-treated and drug-treated groups, the mean FPG concentrations and the stndard deviations for each of the HbA₁ categories were not significantly different between the adult and elderly groups. On the other hand, the mean PPG concentrations and standard deviations in elderly subjects were significantly higher than those for adult subjects at HbA₁ levels less than 8% in the diet-treated group and less than 9% in the drug-treated group. 4) In patients with HbA₁ levels less than 9% and within-subject variability of HbA₁ levels less than 0.2%, the mean coefficient of variation of three serial PPG measurements was not significantly different between adult subjects and elderly subjects. In the elderly diabetics, the interindividual variability of PPG for a given HbA₁ was larger than those of FPG in the eldrely and larger than FPG and PPG in the adult diabetics.