Objectives: The purpose of this study was to investigate the blood biochemical characteristics, comorbidities, dietary intake, and other risk factors leading to poor glycated hemoglobin (HbA1c) control in elderly Korean diabetes patients over 65 years of age. Methods: Data from the 4th (2007-2009) and the 7th (2016-2018) Korea National Health and Nutrition Examination Surveys (KNHANES) were used. Socio-demographic characteristics (age, gender, region, household income, education level, marital status, nutrition education, diabetes duration and diabetes treatment), lifestyle characteristics (drinking, smoking, regular walking, and subjective health perception), anthropometric characteristics (height, weight, and waist circumference), blood biochemical characteristics (HbA1c, high- density lipoprotein cholesterol, triglycerides, total cholesterol, blood urea nitrogen, and blood creatinine), co-morbidities (obesity, hypertension, hypercholesterolemia, hypertriglyceridemia, and anemia), energy and nutrients intake, food group intake, and HbA1c control-related risk factors were compared. Results: Compared to the 4th survey, the 7th survey showed an increase in diabetes prevalence among men, an increase in the prevalence of diabetes in the older patients, and an increase in the duration of diabetes. The energy ratio from carbohydrate consumption in the 7th survey was lower than in the 4th. Compared to the 4th survey, thiamine and riboflavin intake had improved, and the intakes of vitamin A, vitamin C, and niacin had worsened in the 7th. A comparison of food group intakes showed that there was a decrease in the consumption of whole grains, potatoes, and milk and an increase in the intake of beverages and alcoholic beverages. The risk factors for poor control of HbA1c were the duration of diabetes and co-morbid hypertriglyceridemia in the 4th survey, whereas subjective health perception, obesity, and hypercholesterolemia as co-morbidities were found to be risk factors in the 7th in addition to the risk factors highlighted in the 4th survey. Conclusions: For the future management of elderly Korean diabetes patients, greater care is indicated for men over 75 years, and those with low levels of education. It is necessary to increase the intake of milk and vegetables, and reduce the intake of beverages and alcoholic beverages. In addition, it is necessary to reduce the incidence of obesity, hypercholesterolemia, and hypertriglyceridemia for proper control of blood sugar.