[Insulin therapy in elderly patients with diabetes mellitus]

Insulin therapy is an effective measure of improving glucose control even in elderly patients with type 2 diabetes. However, it is controversial whether insulin therapy does disturb the quality of life (QOL) as well as cognitive function in the elderly. In our previous study of 455 diabetic patients, the well-being as assessed by the morale scale was similar in three treatment groups. In contrast, the symptom-burden, social burden, and worry about diabetes as assessed by the Elderly Diabetes Burden Scales was more increased in insulin-treated group as compared to the diet-treated group after adjustment for age, gender, HbAlc, frequency of hypoglycemia, microangiopathy, macroangiopathy, and social support. In another study of 213 patients, MMSE scores were similar among treatment groups, while attention and learning were most impaired in insulin-treated groups after adjustment for age, gender, HbAlc, and duration of diabetes. Although the mechanism for the association between insulin treatment and cognitive impairment is unknown, hyperglycemia, hypoglycemia, and cerebral complications in insulin-treated patients may be possible explanations. Whatever mechanism may be involved, hypoglycemia should be considered especially if unexpectedly low HbAlc (< 6.5%) is observed or atypical neuropsychological symptoms appear. It is unknown how insulin withdrawal is successful in elderly diabetic patients. Using rapid or ultrarapid insulin injections three times daily, good glucose control achieved the goal of plasma glucose level of < 140 mg/dl before meals and at bedtime. Then, insulin therapy was converted to oral treatment of glimepiride (2 to 6 mg/day) and/or voglibose (0.6 mg/day) in 30 patients with poorly controlled Type 2 diabetes. About 83% of the patients were successful in the insulin withdrawal according to the criteria of HbAlc levels after two months < 8.0%. After removal of glucose toxicity, insulin withdrawal should be attempted to improve QOL in elderly patients with diabetes mellitus.