Nutritional challenges in the elderly with diabetes

1. Nutritional status and diabetes in the elderly 

According to the Framingham Heart Study data, men and women with diabetes who are 50 years and older live an average 7.5 and 8.2 years less than individuals without diabetes [1]. Nutritional factors play a significant role in modulating all the traditional risk factors for atherosclerotic disease. Appropriate dietary changes in the setting of diabetes are a critical task in the pursuit of healthy aging in this subgroup. Diabetes in the elderly increases the risk of suboptimal nutrition, hospitalizations, nursing home admissions, and physical disability that substantially impairs quality of life [2], [3]. Minorities living in urban areas of the US are prone to poor nutrition and have increased rates of obesity, glucose intolerance and diabetes [4]. Community-dwelling older adults with diabetes are treated less vigorously than younger persons with diabetes, and many of them do not achieve targets for glucose control that are generally advocated by professional organizations [5].

The overlap of malnutrition and glucose intolerance in older people is common but frequently overlooked. The prevalence increases with frailty, physical infirmity, and institutionalization. In the US, about 16% of elderly persons living in the community are undernourished. These figures rise to 59% in long-term care institutions and 65% in acute care hospitals [6]. Malnutrition encompasses both under-nutrition, due to a deficiency of nutrients, and over-nutrition, resulting from overeating and lack of physical activity. Protein-energy malnutrition is a significant cause of weight loss among older people. “Failure to thrive” refers to a decline in functional status disproportional to disease burden, manifested by a weight loss greater than 5% from baseline. It may result from a variety of causes including protein–energy deficiency, loss of muscle mass and endurance, cognitive impairment, and depression. The latter is a particularly prevalent cause in the elderly with diabetes [7]. Age-related complications like digestive, oral, and dental problems, altered absorption of nutrients, declining renal function, functional disability, dementia, acute or chronic diseases and medication-related issues compound the scenario. Many elderly experience social, domestic, and economic changes. The presence of diabetes adds to the severity of these problems and increases the burden of daily self-care activities. To accurately recognize and treat nutrition-related issues among older adults, comprehensive assessment and screening tools, as well as interventions manuals that identify those who are at risk of malnutrition, are available [8], [9].

2. The connection between diet, aging, and glucose metabolism 

The prevalence of diabetes increases with age, and is highest in those older than 60 years. The rate of metabolism slows down with advancing age due to a decrease in lean body mass and increasingly sedentary lifestyle, resulting in a reduced daily energy requirement (Table 1). Underlying pathophysiologic mechanisms include an increase in insulin resistance related to weight gain and physical inactivity that is central to the pathophysiology of type 2 diabetes and the metabolic syndrome [10]. A progressive failure of insulin production from the pancreatic beta cells may be a pre-programmed genetic defect or a natural concomitant of the aging process [11]. The emergence of postprandial hyperglycemia is followed by fasting hyperglycemia. Lifestyle modifications that include efforts at weight loss and physical activity lead to improved insulin sensitivity and can prevent glucose intolerance and type 2 diabetes mellitus in older adults. Interestingly, recent evidence suggests that the rate of carbohydrate digestion and absorption may influence the development of type 2 diabetes in the older individual. The health, aging and body composition study [12] prospectively cross-sectionally analysed dietary glycemic index and glycemic load of 2248 adults aged 70–80 years with measures of glucose metabolism and body fat distribution. An association between dietary glycemic index and selected predictors of type 2 diabetes such as hyperinsulinemia and centripetal obesity was seen.

Table 1. Factors affecting glucose metabolism with age.

	Resistance to insulin-mediated glucose uptake
	Progressive reduction of insulin secretion form the pancreas
	Changes in body composition: relative increase adipose tissue
	In relation to muscle mass
	Changes in food intake, timing, and composition
	Impaired mobility and physical activity
	Psychological factors, stress, and isolation
	Use of medications that impair insulin sensitivity, release, or action
	Genetic and ethnic influences

3. Diet and lifestyle interventions in older diabetic persons 

Studies have investigated the impact of nutritional and lifestyle changes in the elderly with diabetes. Dye et al. [13] identified factors that affect the nutrition and exercise behaviors of persons over the age of 55 with type 2 diabetes by conducting focus groups interviews to determine primary health concerns and health behaviors, favored learning modalities, barriers to learning, food preferences, and exercise preferences. The following major themes were identified: some risk factors for diabetes and heart disease seemed more pertinent to the subjects than others; perceived susceptibility for serious outcomes of diabetes could occur through vicarious learning; willpower, often obtained through faith, was necessary for successful behavior change; effective modification of behavior and building self-efficacy started with small steps; and intrinsic reinforcement was necessary for behavior change. A nutrition education intervention on improving the intake and behaviors related to whole grain foods in meal recipients in senior centers [14] involved a sample of 84 participants with a mean age of 77 years who completed a pretest, an educational intervention, and a post-test. Following the intervention, participants were more likely to be knowledgeable about one or more correct ways to identify whole grain foods and reported an increased intake of whole grain bread, cereal, and crackers. Older adults with diabetes can thus benefit from nutrition education designed to improve knowledge and skills necessary.

In spite of the plethora of advice available, very few diabetes education programs have been designed specifically for older adults. Miller and others [15] evaluated a randomized intervention to improve food label knowledge and skills in diabetes management among adults aged 65 years and older that included 10 weekly group sessions led by a dietitian incorporating information processing, learning theory, and social cognitive theory principles. The experimental group had greater improvement in total knowledge scores, positive outcome expectations, promoters of diabetes management, decision-making skills, fasting plasma glucose, glycated hemoglobin, and total cholesterol than the control group. Thus, correctable health deficits in the elderly can be assessed through screening protocols [16].

The American Dietetic Association advocates that the public should consume adequate amounts of dietary fiber from a variety of plant foods [17]. The recommended intake of 20–35g/day for healthy adults is not usually met because of low intake of fruits, vegetables, whole and high-fiber grain products, and legumes. Consumption of insoluble dietary fiber lowers blood cholesterol levels and reduces blood glucose and insulin levels. A diet adequate in fiber-containing foods usually has fewer calories, fat, and refined sugar, and is also usually rich in micronutrients and nonnutritive ingredients that have additional health benefits. A fiber-rich meal is processed more slowly in the gastrointestinal tract, thus promoting satiety. These salubrious features of a high-fiber diet promote the treatment and prevention of overweight, obesity, cardiovascular disease, and type 2 diabetes. Even with a fiber-rich diet, however, a supplement may be needed to bring fiber intakes into a range adequate to prevent constipation.

The dietitian, working with other members of the health care team, plays a very important role in developing a care plan for the older person with diabetes [18]. Nutrition education should be individually tailored and should incorporate patience, kindness, humor, understanding, and above all a respect for the differences that make each older person an individual. Skills at multifaceted assessment are necessary to pinpoint challenges in nutritional care, be able to synthesize all the information obtained in order to creatively design a workable dietary intervention, and adapt instruction techniques and tools for a wide variety of educational needs and abilities. Attributes to possess for successful outcomes are knowledge, skill, experience, astute judgment, and sincere caring. The experience and qualifications of the educator delivering the educational components would intuitively seem important. In one study, the knowledge, design and content scores of education were significantly higher in the certified diabetes educator registered dietitians (CDE-RDs) compared to those of the non-certified diabetes educator registered dietitians (non-CDE-RDs) [19]. A “Food Guide Pyramid for Older Adults” is available for use in the elderly population (Fig. 1). The American Diabetes Association (ADA) Diabetes Food Pyramid (available at http://www.diabetes.org/nutrition-and-recipes/nutrition/foodpyramid.jsp) divides food into six groups. The largest group consisting of servings of grains, beans, and starchy vegetables forms the base. The smallest group comprising of fats, sweets, and alcohol is at the top of the pyramid; patients with diabetes are advised to consume sparingly from this food group. In order to formulate a meal plan tailored to the individual goals, the ADA recommends that individuals with diabetes consult a registered dietitian (RD) or certified diabetes educator (CDE).

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Fig. 1. The food guide pyramid for older adults. From: Tufts University, 2002: TUFTS food guide pyramid for older adults. Available at http://nutrition.tufts.edu/docs/pyramid.pdf, accessed 8 February 2009.

4. Economic factors and psychosocial support 

Low income individuals with diabetes are at particularly high risk for poor health outcomes. A cross-sectional study was conducted using an urban, diabetes education center database [20] demonstrated that low income patients presenting to the diabetes clinic were older and heavier than high income patients. Overall medication use was higher among the lower income group. This suggested that differences in clinical profiles were not the result of under-treatment and implicated lifestyle factors as potential contributors. In the National Health and Nutrition Examination Survey (NHANES III), socio-economic status, as measured by education and income, was not associated with whether or not individuals are likely to have undiagnosed diabetes [21]. This finding suggests that screening for type 2 diabetes should focus on those adults who are at risk for diabetes in general (based on age, racial/ethnic groups, obesity and other clinical risk factors) and that socio-economic characteristics are unlikely to provide further information.

Higher levels of perceived family support and greater self-efficacy were associated with higher reported levels of diet and exercise self-care [22], reinforcing the importance of family dynamics in the elderly. Diabetes educators and healthcare providers should consider involving the entire family in the management of older patients with type 2 diabetes. Data also validate the Transtheoretical Model, where those in the action stages displayed healthier eating [23]. They also indicate that demographic and psychosocial factors may mediate readiness to change diet. Drawing on the social cognitive theory and social support literature, a qualitative study explored how spousal support influences dietary changes following a diagnosis of type 2 diabetes in middle-aged and older adults [24]. Analyses revealed five core themes related to dietary adherence: control over food, dietary competence, the degree of commitment, spousal communication, and coping with diabetes. These findings help to develop more effective, targeted nutrition messages and programs to provide specific knowledge and skills.

5. Diabetes medications, meals, and food-related glycemic excursions 

The clinically important extrinsic modifiers of glycemic levels include diet, medications, activity, chronic illness, and stress. Traditionally, providers have concentrated their therapeutic efforts at controlling fasting and average glucose values. Mealtime glucose excursions, such as those occurring in an absorptive state, are also responsible for overall glucose burden. With advancing age, post-meal glucose glycemic excursions are the initial abnormality that progress to fasting and pre-meal elevations. Mechanisms by which post-meal glucose elevations and glycemic variability carries an increased risk of endothelial dysfunction, oxidative stress, and possibly vascular complications, perhaps independently of the HbA1c level [25]. Acute elevations of plasma glucose concentrations trigger an array of tissue responses that may contribute to the development of vascular complications, especially in the older person with diabetes [26]. The ominous finding is that post-prandial glucose may be a risk factor for cardiovascular disease and chronic diabetic complications [27]. Simple clinical characteristics identify subsets of diabetic patients with frequent post-prandial hyperglycaemia. Thus in multivariate analysis adjusted for pre-prandial glucose levels, older age, longer duration of diabetes, absence of obesity, hyperlipidemia, and hypertension were significantly associated with greater glucose excursions after meals [28].

The American Geriatric Society’s stance is that a person’s functional capacity and not age should determine the best treatment modality individualized to each situation [29]. Diet and exercise form the cornerstone of therapy of older persons. The importance of diet and lifestyle changes is reinforced in the American Diabetes Association and the European Association for the Study of Diabetes consensus algorithm released recently [30]. Oral agents provide a valuable armamentarium, although there may be a propensity to side effects to many of the medication classes currently available. Metformin is a useful first-line agent that may be initiated along with lifestyle modifications or shortly thereafter, but may be contraindicated because of the presence of renal insufficiency. Sulfonylureas should be used cautiously since the elderly are prone to hypoglycemia. Thiazolidinediones reduce insulin resistance but also cause fluid retention and may precipitate edema and congestive heart failure. The effect of aging on metabolism and pharmacokinetics also need to be taken into account. In general, treatment strategies follow a continuum over time from lifestyle modification to intensive management [31]. Intensive insulin therapy, through the use of either multiple daily injections (MDII) or continuous subcutaneous insulin infusion (CSII, or insulin pump therapy), has been demonstrated to be beneficial in the elderly [32], [33]. Such insulin regimens, although complex, should not be withheld from older patients if they are otherwise capable of understanding and adhering to the treatment. General practitioners and patients alike have reluctance to initiating insulin, the so-called phenomenon of ‘clinical inertia’. The expertise of endocrinologists may be highly desirable in this regard. A big advantage of tailoring insulin to patients’ glucose profiles is a more precise control of meal-related hyperglycemia, as long as a physiologic ‘basal-bolus’ insulin regimen is used and timing of injections to food is achieved. In addition, the use of carbohydrate counting or exchange lists gives more flexibility to the older adult with diabetes. It must be kept in mind, however, that there is a lack of evidence-based outcomes regarding intensive management in older patients, and the risk-benefit ratio should always be calculated in the individual person. Hypoglycemia and hypoglycemia unawareness is more deleterious in the elderly and should be avoided. Properly conducted studies evaluating safe and effective use of diet and insulin treatment algorithms are needed.

6. Nutrition in the management of complications and co-morbidities 

Maintenance of adequate hydration may be challenging in the elderly suffering from significant hyperglycemia, yet is an important parameter to monitor. Changes in thirst perception, cultural and eating habits, and cognitive of functional impairment may play a role. Hypertension is a common comorbid health condition in older patients with diabetes. Individuals with diabetic nephropathy may need both sodium and protein restriction. Although protein needs for the aged are the same or slightly higher than other adults, a moderate reduction may be in order if advanced renal insufficiency is present. Less than half of non-institutionalized older population with diabetes who have indications for angiotensin-converting enzyme and angiotensin-receptor blockers are actually receiving them [34]. Diabetes is a “cardiac risk equivalent” that mandates adherence to a low-fat, step 1 or step 2 diet as advised by the National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) III guidelines (updated in 2004 to include more aggressive targets in patients with diabetes) [35]. The risk of peripheral vascular disease in persons with diabetes mellitus increases with advanced age, necessitating clinical vigilance [36]. Individualized and comprehensive prevention efforts are required to address the complicated and diverse nature of the diabetic foot in the elderly patient. A multidisciplinary management strategy addressing glucose control, provision of foot care education, and appropriate foot wear yields the best results. Development of lower extremity ulcers and their proper assessment is dependent on physiologic and socioeconomic factors. To help ulcer-related complications and prevent lower leg amputations, clinicians must address glucose control; the cost of supplies; the importance of offloading, nutrition, and exercise; and challenges inherent to impaired eyesight, dexterity, and ability to self-care. Maintaining optimal nutrition in order to prevent and manage foot problems remains paramount.

Evidence is increasing that oral health has important impacts on systemic health. Data describing the prevalence of dental caries and periodontal diseases in the older adult population has been published [37]. Periodontal infection is a risk factor for poor glycemic control in type 2 diabetes; however, studies on relationships among oral health status, chronic oral infections, and certain systemic diseases, specifically type 2 diabetes and aspiration pneumonia, need to be conducted. These diseases increase in occurrence and impact in older age groups. There is evidence to support recommending oral care regimens in protocols for managing type 2 diabetes and preventing aspiration pneumonia [38].

Because more than a third of people over age 65 are edentulous, the maintenance of optimal nutrition and intake of adequate cellulose fiber may be difficult to achieve. Routine dental exams and a liberal fluid ingestion usually help to prevent the tendency to constipation in these circumstances [39]. Many diabetic individuals complain of dry mouth (xerostomia), a condition that can affect oral health, nutritional status, and diet selection. Older adults with poorly controlled diabetes may have impaired salivary flow in comparison with subjects with better controlled diabetes and nondiabetic subjects, yet they may not have concomitant xerostomic complaints [39]. Routine questioning may not uncover the problem, and maintaining a high index of suspicion and meticulous physical examination are necessary.

7. Nutritional aspects in the community-dwelling elderly with diabetes 

The amount of food sufficiency and affordability influences the degree of adherence to dietary self-care behaviors. The nutrition and function study (NAFS) [40] examined whether homebound older adults with diabetes were at greater risk for heightened food insufficiency despite regular receipt of home-delivered meals. Not only did food-sufficiency status diminish over time in this sample, but it became or remained worse for older adults with diabetes. The investigators recommended developing community strategies that integrate nutrition with diabetes care plans, thus supporting a multidisciplinary, chronic care model to improve diabetes management and outcomes in the older population. An Australian study [41] concluded that only 4.3% of subjects with diabetes met all macronutrient recommendations, only 2.4% had adequate fiber intake, and the calculated glucose load of the diet in older individuals was only slightly lower than that of younger people. Thus only a small percentage was able to meet nutritional recommendations for optimal diabetes management. Diet and exercise practices obtained from a nationally representative sample of US adults with type 2 diabetes, many of whom were older than age 50 [42], showed that 36% of the sample was overweight, 31% reported no regular physical activity, and 62% percent ate fewer than five servings of fruits and vegetables per day. Almost two thirds of the respondents consumed >30% of their daily calories from fat and >10% of total calories from saturated fat. Lower income and increasing age were associated with physical inactivity. In conclusion, the majority of individuals with type 2 diabetes was overweight, did not engage in recommended levels of physical activity, and did not follow dietary guidelines for fat, fruit, and vegetable consumption.

As the epidemic of diabetes rages on, ensuring proper nutritional intake is an important challenge facing communities world wide. The presence of senility and frailty in the elderly person suffering from diabetes makes this task even more difficult. Community nurses will have increasingly larger caseloads of elderly patients with diabetes [43]. Home visits and interactions with family members will require special attention. It is important that visiting nurses assess the patient’s understanding of the disease and its treatment. The aim of good diabetic control in the elderly person may not be the same as in other age groups. Amelioration of symptoms is foremost, although reducing morbidity from complications is a worthy long-term goal [44]. The degree of glycemic control should be decided on an individual basis. Factors that affect the patients’ quality of life and their ability to manage their condition should be assessed. The importance of diet, blood glucose monitoring and adherence to prescribed medications are important aspects of care for the frail elderly with diabetes [45].

The principles of sound nutrition remain as true in the older person with diabetes as in younger ones [46]; however, financial considerations have to be taken into account. The social dynamics that affect lifestyle changes include retirement, widowhood, or moving into an assisted living facility, all of which can cause emotional instability and impact the quantity and quality of food consumed. Anticipation of the cost of food and the provision of low-cost alternatives should be sought. Resources available for adequate short- and long-term nutritional supplementation include adult day care centers, social services, “meals-on-wheels”, in-home personal aides, aging centers, food stamps, and community nutritional sites [47]. Food palatability and consistency as well as cultural preferences and life-long culinary habits are important considerations in the diabetic patient for optimal weight maintenance and glucose control. Useful points to keep in mind when addressing nutritional issues in the elderly with diabetes are listed in Table 2.

Table 2. Key points to take into consideration with regard to nutrition in the elderly patient with diabetes.

	•The prevalence of diabetes increases with age and is likely to coexist with other chronic health conditions •Appetite changes, palatability, dietary restrictions, and psychosocial issues becomes increasingly important factors in the elderly •Nutritional should be guided by glycemic control, long-term risk of vascular complications, and by the patient’s preferences and quality of life •Awareness of nutritional guidelines and tailoring them to the elderly diabetic patient is a prudent approach

8. Conclusion 

Abnormal glucose tolerance is present in more than 60% of adults older than 60 years of age as a result of a decrease in glucose tolerance as a result of decreased insulin sensitivity and impairment of pancreatic beta-cell function. The elderly diabetic population stands to benefit enormously from streamlining and optimizing diet planning in order to enhance longevity, minimize complications, and improve quality of life. Current diet and lifestyle recommendations for patients with diabetes mellitus mainly focus on young and middle-aged persons. There is a paucity of definitive, long-term studies examining the part that nutrition plays in the overall health and metabolism of older people. In order to meet these challenges, it is imperative to understand the role of dietary factors in the genesis and progression of glucose intolerance and diabetes in the older individual and implement evidences based recommendations tailored to the specific circumstances.