Abstract
We investigated the effect of aging on the level of glycosylated hemoglobin (HbA1) in healthy subjects and diabetic patients. On the basis of our findings in this study, and using the HbA1c level as an index to long-term plasma glucose control, we compared it with the levels of fasting plasma glucose (FPG) and post-prandial plasma glucose (PPG) in different age groups subjected to different therapies so as to explore clinical problems in measuring plasma glucose levels in elderly diabetic patients.
There were significantly positive correlations between HbA1 and HbA1c. In the healthy group examined, the HbA1 and HbA1c levels rose significantly with age. No specific relationship was found between HbA1a+b level and age. Looking for a correlation between the HbA1c level and the antecedent plasma glucose level in different age groups of the diabetic patients subjected to different therapies, we found that, in the subgroups of the "young to middle-aged" (under 60 years old) and the "elderly" (60 and above) patients, and in both the diet-treated group and those treated with the oral hypoglycemic agent (OHA), the HbA1c, level was best correlated with the FPG and PPG levels in the antecedent 3 to 8 weeks.
The coefficient of correlation between HbAI level and FPG and PPG levels in the antecedent 3 to 8 weeks did not vary from one therapy subgroup to another in the young to middle-aged patients. In contrast to this, the correlation coefficient for PPG was significantly lower than that of FPG in each therapy subgroup of the elderly patients. By examination of the mean levels and variances of plasma glucose in the antecedent 3 to 8 weeks in one-percent HbA1C strata of each therapy subgroup of each age group, the elderly group was significantly higher than the young to middle-aged group in PPG average in the over-5% and over-6% HbA1c, strata of the diet-treated subgroup and in the over-5%, over-6% and over-7% strata of the OHA-treated group.
We investigated the variation coefficient of three PPG measurements in the antecedent 3 to 8 weeks in cases under extremely stable plasma glucose control, and found no significant difference in mean coefficient between the elderly group and the young to middle-aged group.
These results strongly suggest that the PPG level varies considerably from one individual to another in elderly diabetic patients.
