Glycemic control is important to improve the prognosis in cirrhotic patients with complications from diabetes. A late evening snack (LES) has been recommended for cirrhotic patients. We investigated the effects of LES on diurnal plasma glucose levels. Subjects comprised 47 patients with chronic viral liver disease (chronic hepatitis, n = 11; cirrhosis, n = 36) treated in the Department of Gastroenterology & Hepatology, Dokkyo Medical University Koshigaya Hospital. Diurnal variations in plasma glucose were first investigated with three meals/day, in accordance with the European Society for Clinical Nutrition and Metabolism (ESPEN) guidelines. Starting the next day, patients were given four meals including a LES, without changing meal content. Diurnal variations in plasma glucose were examined on day 7, and urine C-peptide immunoreactivity (CPR), and homeostasis model assessment insulin resistance (HOMA-IR) were investigated. With a LES, plasma glucose levels in patients with chronic hepatitis were significantly lower 2 hours before and 2 hours after dinner. In cirrhotic patients, significant decreases in plasma glucose levels were seen 2 hours after breakfast, before lunch, and before dinner. Significant decreases were noted in average plasma glucose levels and highest plasma glucose levels with four meals including a LES in patients with liver cirrhosis. This decrease was greater when maximum plasma glucose levels were higher on the three-meal regimen. Improvements in plasma glucose levels were seen with four meals per day, including a LES, in viral chronic liver disease, particularly cirrhosis.