Total management of diabetes mellitus in the elderly

Abstract

Listen

Translate article

The most recent Japanese demographic data confirm that the numbers of both children and adults are gradually and dramatically decreasing. In contrast, the number of older subjects is rapidly increasing, comprising more than 25 % of the total population in 2013. Thus, Japan is now the most aged society in the world. In addition, the 2012 Japanese national health and nutrition survey estimated that approximately 20.5 million subjects were either strongly suspected of having diabetes or had possible diabetes. In regard to age-specific incidence, about 40 % of males and 35 % of females over 60 years are suspected of having or likely to have diabetes. Several factors are proposed to account for this increasing incidence of diabetes and impaired glucose tolerance in the elderly. Sarcopenia, the decreased mass and function of skeletal muscles, is very important because it can induce insulin resistance [1]. Several mechanisms may be involved in the onset and progression of sarcopenia, which is classified as primary or age-related when no other causes are evident. The prevalence of primary sarcopenia in 65–70 year-olds ranges from 13 to 24 %, increasing to more than 50 % in those over 80 years [2]. Sarcopenia is associated with frailty, which is highly prevalent in old age, and confers a high risk for falls, disability, hospitalization and increased mortality [3]. A current systematic literature review has identified that cognitive impairment also has a serious effect on frailty [4]. In 2003, a Japanese survey reported that both the total number and ratio of patients with dementia are increasing year by year. However, a recent report has revised this data, with 2013 results classifying 4.5 million elderly Japanese subjects as having dementia, a greater than 15 % ratio among elderly persons in Japan. Diabetes mellitus is an established risk factor for dementia, with the frequency of vascular dementia increasing from 1.8-fold to 3.4-fold in subjects with diabetes mellitus compared to those without diabetes. On the other hand, the contribution of diabetes mellitus to the risk of developing Alzheimer’s disease is less clear. However, a systematic review based on prospective studies indicates that almost all report risk ratios greater than one. In five well-conducted studies, this excess risk was statistically significant [5]. Thus, diabetes mellitus is likely to increase the risk of Alzheimer’s disease by about twofold. However, the role of diabetic complications as possible mechanisms in the development of dementia has not been well studied. Although acute hypoglycemia may be associated with cognitive impairment in children with type 1 diabetes, no studies have evaluated whether hypoglycemia is a risk factor for dementia in older patients with type 2 diabetes. A longitudinal cohort study followed up for 27 years indicated that a history of severe hypoglycemic episodes was associated with a greater risk of dementia [6]. On the other hand, a famous Japanese cohort study, the Hisayama study, also suggests that diabetes is a significant risk factor for all-cause dementia. Moreover, 2-h postload glucose levels, but not fasting plasma glucose levels, are closely associated with an increased risk of Alzheimer’s disease [7]. Thus, both severe hypoglycemia and postprandial hyperglycemia are associated with cognitive decline, especially Alzheimer’s disease. Rizzo et al. [8] reported that the increase in mean amplitude of glycemic excursions (MAGE) was significantly correlated with a decrease in mini mental status examination (MMSE). Since MAGE is a significant determinant of overall metabolic control, these K. Yokono (&) Kita-Harima Medical Center, Ono, Hyogo, Japan e-mail: yokonok@kobe-u.ac.jp