Underestimation of impaired glucose tolerance and usefulness of a continuous glucose monitoring system in chronic liver disease

Background and Aim The prevalence of glucose intolerance in chronic liver disease patients is high, but glucose intolerance may be overlooked in a single blood test. The purpose of this study is to evaluate blood glucose variability in patients with chronic liver disease by a continuous glucose monitoring system (CGMS) and to examine the discrepancy between hemoglobin A1c (HbA1c) levels estimated from average blood glucose levels and HbA1c. Methods This study included 335 patients with chronic liver disease associated with glucose intolerance. A fasting blood test and 72-h CGMS were performed. The estimated HbA1c was calculated from the average blood glucose level, and the correlation between hepatic functional reserve and blood glucose-related parameters was analyzed. From the obtained data, we created a new formula to calculate HbA1c without using CGMS. Results As hepatic functional reserve decreased, average blood glucose and insulin resistance increased while HbA1c decreased (P < 0.0001). The discrepancy between the estimated HbA1c calculated from the mean blood glucose level and the serum HbA1c (Delta HbA1c) increased as the liver reserve decreased. Using multiple regression analysis, a formula based on fasting blood glucose, HbA1c, body mass index, albumin, and liver function was constructed, and its validity was demonstrated in a study using a different control group. Conclusions Hemoglobin A1c may be underestimated because of decreased hepatic functional reserve. CGMS was useful in assessing accurate glycemic control of blood glucose and in detecting postprandial hyperglycemia and nocturnal hypoglycemia. Patients with chronic hepatic impairment should be corrected for hepatic functional reserve before glycemic control.