Inactive aldehyde dehydrogenase 2 worsens glycemic control in patients with type 2 diabetes mellitus who drink low to moderate amounts of alcohol

Background: Alcohol intake can have hypoglycemic or hyperglycemic effects i n patients with type 2 diabetes mellitus. The present study was designed to investigate the glycemic control of male patients with diabetes mellitus f rom the aspect of the genetic status of alcohol metabolism. Methods: One hundred sixty-three men with type 2 diabetes mellitus were enr olled in the present study. They were all outpatients at the Diabetes Cente r of Saiseikai Central Hospital. The genotype of the aldehyde dehydrogenase 2 (ALDH2) gene of each patient was determined by polymerase chain reaction -restriction fragment length polymorphism (PCR-RFLP), and the patients were divided into those with active or inactive ALDH2 phenotype. We compared th e amount of habitual alcohol intake and clinical data that included physica l findings and blood chemistry of the patients in the active and inactive A LDH2 groups. The glycemic control of each patient was evaluated by the seru m level of HbA1c. Results: Of the 163 patients with type 2 diabetes mellitus, 90 patients had the active ALDH2 phenotype and 73 patients had the inactive ALDH2 phenotyp e. The mean HbA1c level of the active ALDH2 group was nearly the same as th at of the inactive ALDH2 group. However, the HbA1c level of the light-to-mo derate drinkers (1-400 g/week) in the inactive ALDH2 group was highest and was significantly higher than the HbA1c level of the light-to-moderate drin kers of the active ALDH2 group. The HbA1c of the patients with diabetic com plications was higher than the HbA1c of those without diabetic complication s in both the active and inactive ALDH2 groups. However, the HbA1c level of the light-to-moderate drinkers without diabetic complications in the inact ive ALDH2 group was significantly higher and the incidence of 24 hr urinary C-peptide was higher than the respective level of the light-to-moderate dr inkers without diabetic complications in the active ALDH2 group. Conclusions: Habitual light-to-moderate alcohol intake worsens glycemic con trol in diabetic patients who have the inactive ALDH2 phenotype. The data o n 24 hr urinary C-peptide level suggested that increased acetaldehyde after light-to-moderate drinking by inactive ALDH2 diabetic patients may increas e the HbA1c value by the insulin-resistant condition that resulted in hyper insulinemia.