Objective: To study the relationship between the glucose fluctuation and beta cell function in the diabetes mellitus (DM) patients.
Methods: Sixty hospitalized DM patients, 27 males and 33 females, aged (59 +/- 14), with a course of DM (8 +/- 8) years, underwent dynamic blood glucose monitoring by continuous glucose monitoring system (CGMS). Arginine stimulation test was conducted to detect the blood glucose and C peptide. Blood lipids were measured by automatic chemistry analyzer. The relations among fast plasma glucose (FPG), glycated hemoglobin (HbA1c), mean glucose concentration (MBG), mean amplitude of glycemic excursion (MAGE), and incremental value of C peptide (DeltaCP) were studied.
Results: (1) The subjects were divided into five subgroups by HbA1c, 24 h CGMS profiles showed that a progressive deterioration of the glycemic profiles from group 1to 5 associated with increasing levels of HbA1c. The FPG levels were not significantly different between the group of HbA1c < 6.5%, and the group of 6.5% < or = HbA1c < 7%, but the postprandial blood glucose of the latter group was higher than that of the former group. The CGMS curve shifted upward along with the increase of HbA1c level. (2) After adjustment for sex, age, and diabetes duration, positive correlation was found between HbA1cw and FPG, MBGw and FPG, MBG and HbA1c, MAGE and HbA1c, and MBG and MAGE (r = 0.67, 0.66, 0.63, 0.44, 0.39, all P < 0.01), and FPG and MAGE (r = 0.31, P < 0.05). (3) After adjustment for sex, age, and diabetes duration, the DeltaCP was negatively correlated with FPG, HbA1c and MAGE (r = -0.30, P < 0.05; r = -0.39, -0.42, all P < 0.01). MBG was not significantly correlated with DeltaCP (P > 0.05). (4) There was no significant differences in the DeltaCP level when HbA1c < 7%, but decreased when HbA1c > or = 7%. (5) Stepwise regression analysis demonstrated that MAGE firstly entered the equation and DeltaCP was predicted by MAGE, total cholesterol, and HbA1c when DeltaCP was regarded as dependent variable and age, diabetic duration, BMI, waist-to-hip ratio, blood pressure, MBG, MAGE, FPG, HbA1c, and blood lipid were regarded as independent variable (adjusted R(2) = 0.305, P < 0.01).
Conclusion: Glucose fluctuation deteriorates the beta cell function much more than sustained hyperglycemia does.