Management of Diabetes Mellitus in the Nursing Home

Abstract

Diabetes mellitus affects a large proportion of patients in the nursing home. Its management needs to be highly individualized based on clinical and functional status. Several new antidiabetic agents have increased treatment options, but these drugs have not been assessed in the nursing home. To date, there are no clear guidelines for optimizing treatment of patients with diabetes in nursing homes. Significant opportunity exists for medical directors to take a leadership role in the control of this important disease. (Annals of Long-Term Care 1998;6[2]:102)

With the aging of America's population, the number of individuals who develop diabetes mellitus is increasing. Many of these people are admitted to nursing care facilities either for short-term subacute care or for long-term custodial care. Previous studies have shown that approximately 18% of people over the age of 65 have diabetes.1 This percentage includes approximately 9% who are diagnosed with this illness and an additional 9% who meet the classical criteria for this illness but have not been previously diagnosed. It is, therefore, not surprising that diabetes in the nursing home is extremely common, with one major survey reporting that 18.3% of nursing home residents have the disease.2 When undiagnosed cases are included in this assessment, the estimated number of residents with diabetes jumps to 20% to 30%.3

Diabetes mellitus is an expensive disease, with costly treatments required for both maintenance therapy and treatment of complications. The result is that diabetes care in the elderly accounts for approximately 25% of the Medicare budget.4 Complications of diabetes can further erode quality of life by worsening functional abilities. Thus, an important task of medical directors is to facilitate development of a program to assist with management of this common chronic disease.

Several issues make treatment of diabetes in the nursing home population different than in the young or even in older ambulatory populations. The most important factors are the increased prevalence of functional disability and comorbid conditions, both of which increase the complexity of managing diabetes and contribute to the high rate of death among this population.

Treatment to reduce long-term diabetic complications may not be appropriate in some groups of older patients in nursing homes, particularly those who have an extremely short life expectancy. In addition, the high prevalence of dementia--an illness present in one-half of all nursing home residents--significantly impacts the management of diabetes.5 Finally, there is great variability in health status and reason for admission to various nursing facilities, making general guidelines inappropriate in nursing facilities. The need for individualization of therapy becomes even more important in this subgroup of the elderly.

Unfortunately, our knowledge of diabetes in nursing home patients is limited by the lack of investigations in this population, with only a few papers presenting empiric data on older adults residing in nursing homes.6-8 Existing literature does confirm, however, that there are significant opportunities for improvement of metabolic control.

Several lines of evidence suggest that improved diabetes management may be more important in older adults with diabetes in the nursing home than in either younger or older populations in the community. Cognition is impaired by hyperglycemia,9,10 which is at least partially reversed with normalization of glucose levels.11 If hyperglycemia is not treated, however, it may further contribute to the functional decline seen in demented patients. In addition, hyperglycemia decreases pain thresholds, impairs vision, and increases the risk for falls by increasing the risk of dehydration--all of which may have a significant impact on this already impaired group in a nursing home.12 There is also evidence that diabetic complications may occur more rapidly in the elderly. Unfortunately, the risk of hypoglycemia is also much higher in this group, and it should be assumed that most patients in the nursing home setting are unable to perceive or communicate hypoglycemic symptoms.

Despite the potential benefits of treatment, no definitive evidence exists that improved metabolic control results in improved long-term outcomes in this population. Indeed, treatment is largely based on clearly observed negative outcomes in untreated cases of diabetes mellitus, correlations done between abnormal blood glucose and more rapid development of complications, and extrapolation from intervention studies done in much younger patients and predominantly in patients with type 1 diabetes.13-15 In this regard, several studies are pending that address the issue of improved metabolic control of type 2 diabetes, but few if any studies are being performed in nursing home populations.

Diagnosis of Diabetes Mellitus

Despite increasing carbohydrate intolerance in older adults, the criteria for diabetes diagnosis in the elderly remain unchanged. The new American Diabetes Association (ADA) guidelines for diabetes require either two fasting glucose levels over 125 mg/dl or classic diabetic symptoms and a single random glucose level equal to or greater than 200 mg/dl.16 The third criterion, an abnormal glucose tolerance test, is rarely necessary for diagnosis of diabetes mellitus in older adults.

Once the diagnosis is made, treatment options need to be discussed with the patient or family. Despite the substantial burden of other illnesses, and in some cases terminal conditions, geriatric patients diagnosed with diabetes mellitus often have the same anxiety and need for information as younger patients. Therefore, the same care is necessary in discussing the diagnosis with patients and families as with younger patients.

Nonpharmacologic Treatment of Diabetes Mellitus

Once the diagnosis of diabetes mellitus is made, treatment needs to be carefully geared to the individual's clinical circumstances. The need for individualization is greater in this population than in any other. Goals of treatment need to be matched to overall functional status and life expectancy. Suggested treatment goals by diabetic subgroup are listed in Table I.

The decision to treat patients with obvious symptoms (eg, polyuria, polydipsia) is an easy one. However, the more complicated issues are whether to treat early asymptomatic diabetes in this population and the appropriate intensity of treatment for symptomatic patients with diabetes in the nursing home. One useful approach for treating symptomatic diabetes is to identify separate goals of treatment by subset of nursing home patients. In the simplest form, three groups of nursing home patients exist.

Minimally Impaired Patients

These are people receiving subacute care or younger people receiving chronic care for whom guidelines developed for younger ambulatory populations may be appropriate. This is the smallest subset of nursing home residents with diabetes mellitus in most facilities.

Demented or Complex Medical Patients

People in this second group have a life expectancy of approximately 1 to 8 years.They are functionally disabled or chronically demented, which may decrease the value of treatment to reduce long-term complications. However, patients in this population may already have had the disease for several years (recognized or unrecognized) and may be at high risk for early development of complications. Risk and benefit of therapy need to be carefully weighed, and intensity of treatment needs to be highly individualized based on cognitive and functional status as well as severity of the disease. This is the largest subset of nursing home residents with diabetes mellitus.

Terminally Ill Patients

These are people who are in the nursing home for palliative or terminal care for whom treatment should be aimed only at avoidance of classic diabetes symptoms, such as increased thirst or polyuria.

Medical Nutrition Therapy

The cornerstone of diabetes management has long been diet. Dietary restriction for patients with diabetes may be less critical in the nursing home, where residents are at significant risk for undernutrition, due to decreased caloric intake and weight loss commonly seen in this setting.

One study performed in a nursing home demonstrated only modest increases in fasting glucose in well-controlled nursing home residents with diabetes who had short-term (4 weeks) conversion to a regular unrestricted diet.17 This study's results and other data have influenced a subcommittee of the American Diabetes Association to modify its recommendations for medical nutrition therapy for residents with diabetes in institutional settings.18 The subcommittee has proposed a liberalization of previously suggested restricted diets. Instead, a regular diet is proposed with consistent levels of carbohydrate in meals or snacks. In addition, the designation of an ADA diet is being strongly discouraged and is no longer endorsed by the ADA. Dietary restriction is particularly problematic in the nursing home setting, where patients with diabetes are more frequently underweight than overweight.6 Instead, the subcommittee advises that food not be restricted and that moderate use of sucrose-containing foods be permitted. Diabetic control should be maintained by adjusting medications, not food, for patients in the nursing home, with the exception of younger patients who are in the facility for rehabilitation.

Exercise

Exercise is another important component of diabetes management that contributes significantly to maintenance of physical functioning. Studies indicate that exercise in the nursing home is possible, including weight training.19 Aerobic exercise, which is likely to be the most appropriate intervention for patients with diabetes, has shown much less benefit in older persons20,21 and has not been tested in nursing home populations.

Any exercise regimen should be accompanied by a thorough preexercise evaluation, including an exercise stress test.22 Reimbursement is limited for maintenance therapeutic exercise activities, and more research needs to be done on this population before widespread use of exercise in this frail population can be recommended.

Pharmacologic Treatment

The decision to use pharmacologic treatments for patients with diabetes should take into account several issues, including underlying cognitive status, goals of treatment, and expected longevity (Table I). If the disease is deemed sufficiently severe that it requires treatment, a wider choice of antidiabetic agents is now available. Oral treatments for patients with type 2 diabetes work best in those whose fasting plasma glucose is less than 300 mg/dl. Insulin therapy is often required as the severity of diabetes progresses. Combinations of various oral agents and insulin have been studied, but none of these assessments have included individuals from nursing homes.

Sulfonylurea Agents

Sulfonylurea agents have historically been the mainstay of diabetes treatment in older patients. It is now generally recommended that treatment be initiated with a second-generation agent. Individuals who are well controlled on first-generation agents in most situations do not need to have their treatment changed (with the exception of those patients receiving chlorpropamide, which should not be used in the elderly). Of the two most widely prescribed second-generation agents, glipizide appears to be associated with less hypoglycemia than glyburide. Glyburide actually had a similar rate of hypoglycemia as chlorpropamide in one recent epidemiologic study, suggesting that it should be used with great care in this population.23

Biguanides

Metformin is the only drug of the biguanide class available in the United States. Metformin's mechanism of action is to decrease hepatic gluconeogenesis. This drug is similar to sulfonylurea drugs in its potency, and it typically lowers glycosylated hemoglobin A (HbA1c)by 1% to 2%. On theoretical grounds, metformin would appear to be of higher risk as an antidiabetic agent in older adults because it can cause lactic acidosis in rare cases, particularly in those patients with renal failure.24 It is not recommended for men whose creatinine is greater than or equal to 1.5 mg/dl, for women whose creatinine isgreater than or equal to 1.4 mg/dl, or for individuals who have abnormal creatinine clearance.25 These groups may include most nursing home residents, who, on average, are in their mid to late 80s.

Nursing home residents frequently have impaired renal function despite normal serum creatinine levels. An 88-year-old woman with 60 kg of lean body mass living in a nursing home who has a creatinine level of 1.0 mg/dl would have a predicted glomerular filtration rate of 37 ml/minute. Assuming the same creatinine clearance in a 45-year-old man with 75 kg of lean body mass would result in a predicted creatinine of 2.7 using the Crockcroft-Gault formula to estimate creatinine clearance.26 It therefore seems likely that nursing home residents would be of high risk in this group. It is also useful to note that metformin should be discontinued for at least the 48-hour time period prior to and following contrast-enhanced radiologic studies.27

Alpha-Glucosidase Inhibitors

Acarbose is the only commercially available drug from this new class of competitive inhibitors of carbohydrate digestion. Its use does not entail a risk of hypoglycemia, it produces few druginteractions, and it has produced no other known serious adverse events. Unfortunately, flatulence is common with the use of this drug; thus, the drug requires slow titration of dosage. Although this medication has not been specifically studied in elderly populations, recent phase IV trials indicate that acarbose is a safe and effective agent in elderly patients.28

Thiazolidinediones

Troglitazone has recently been approved for patients who have type 2 diabetes as monotherapy or in combinations with sulfonylurea agents or insulin. This drug's mechanism of action is to reduce liver gluconeogenesis and to increase muscle uptake of glucose. Troglitazone-related hepatotoxicity is of concern, and there is limited clinical experience with this drug. Currently, it is recommended that patients started on this drug should have their liver enzymes monitored monthly for the first 6 months and then every 2 months for the subsequent 6 months of therapy. Thereafter, periodic monitoring is recommended as well. Its significant expense (more than $5 per day at recent wholesale prices) greatly limits its use because similar control of diabetes can be obtained with far less expense with other agents.29

Insulin Therapy

Many patients in the nursing home have diabetes of such severity that they require insulin therapy. Although human insulin is rapidly supplanting animal insulin, at least one study suggests that older patients have greater awareness of hypoglycemia symptoms with beef/pork insulin than with human insulin.30

Lispro insulin is a recently released synthetic insulin that has a shorter onset and duration of action. This insulin is typically given three times a day with meals (typically with an evening dose of a long-acting insulin).31 Limited short-term studies have not confirmed a substantial benefit over similar use of regular insulin in terms of reducing HbA1c levels. One potential advantage of this agent is to give an injection just prior to a meal (or in some cases, at the completion of a meal) to nursing home residents who have unpredictable eating patterns resulting in hypoglycemia. This type of prn treatment at mealtime might reduce hypoglycemia reactions and still reduce postmeal hyperglycemia, although this regimen has not been studied in the elderly.

Monitoring of Therapies

Monitoring of diabetic control is accomplished using three general methods. The first is the monitoring of plasma glucose by a laboratory assay. This approach is costly, and the additional precision in measurement is usually not worth the extra cost except on an occasional basis. The second approach is the use of finger-stick glucose as a measurement of diabetic control over time. A third option involves the use of more long-term measures to determine diabetic control over a period of days or weeks, including monitoring HbA1c and fructosamine.

In the nursing home, measurement of fasting blood glucose by laboratory assay is a very common measurement for diabetic control. It is common to find routine orders that include a monthly fasting glucose level. It should be noted that this test as a sole measure of diabetes is generally thought to be inadequate. Significant fluctuations of plasma glucose can occur during the day, although fasting glucose levels are normal. More frequent measurement is preferred, typically with finger-stick determinations using glucometers. When an individual is being stabilized on a new medication regimen, it is probably appropriate to measure glucose levels prior to each meal and at bedtime. For stable patients with diabetes, finger-stick glucose measurements by glucometer can be taken preprandially and 2 hours postprandially on a weekly basis and as needed if there is a change in clinical status. There is a wide variability in the accuracy of meters for the measurement of plasma glucose.32 A high-quality glucometer with sufficient sensitivity and specificity should be used.

Hemoglobin A1c or glycohemoglobin is often used as the optimal measurement of diabetic control. Hemoglobin A1c provides a good average measure of serum glucose and can be helpful in determining long-term management strategy. Hemoglobin is measured by two different methodologies: total hemoglobin A and the A1c fraction of hemoglobin. Considerable variability in measurement criteria in laboratories exists, hampering comparisons between laboratories. In addition, several clinical states that are common in older adults in nursing homes interfere with measurement of these levels. Because the average life span of hemoglobin is approximately 90 days, some specialists have recommended a measurement frequency of four times a year. A recent study evaluating diabetic control in the ambulatory Medicare population indicated that only 20% of patients with a diagnosis of diabetes received a single HbA1c measurement in the previous year, suggesting a low compliance with this guideline.32

Another less costly measure is the use of serum fructosamine. It similarly responds to elevations in the plasma glucose and has less potential to be influenced by other medical conditions. The shorter half-life of serum protein (approximately 2 weeks) makes this test more susceptible to fluctuations in diabetic control. However, 2 weeks is a reasonable time in most circumstances to measure diabetic control.

Monitoring for Diabetic Complications

Hypoglycemia is the most feared short-term complication of diabetic treatment because it can result in long-term disability, particularly in cognitively impaired individuals who are living in the nursing home. Its frequency in the nursing home population is unknown, but its incidence rises exponentially with age, and it is probably a major risk in this population. Why hypoglycemia occurs more commonly with advancing age is not clear, but documented abnormalities in counterregulatory hormonal responses are likely to be a significant factor.34

Determining what constitutes hypoglycemia, as well as what interventions are appropriate, is a controversial area in diabetic care. The three classic criteria for the diagnosis of hypoglycemia are a plasma glucose level below 50 mg/dl, signs and symptoms of hypoglycemia, and demonstration of reversibility by giving carbohydrates.35

Signs and symptoms of hypoglycemia include adrenergic symptoms, such as sweating, hunger, anxiety, nervousness, tremulousness, and palpitations. Also, neuroglycopenic symptoms--such as headache, weakness, tiredness, blurred vision, confusion, amnesia, dizziness, difficulty waking, feeling cold, or having paresthesias can be noted with hypoglycemia.35 Adrenergic symptoms are often lacking in the elderly, and neuroglycopenic symptoms are often easily confused with those of other underlying chronic diseases that have caused the patient to enter the nursing facility (eg, dementia, debilitating disease, or functional disability). Physical signs also noted occasionally with hypoglycemia include fever, hypothermia, arrhythmias, increased pulse pressure, and distal neuropathy. These relatively nonspecific signs can add to diagnostic certainty when classic signs are noted but are generallynondiagnostic when they are the only presenting finding. Dementing illness, in particular, complicates and impedes reporting of hypoglycemic symptoms.

A recent point prevalence study of nocturnal finger-stick glucose levels of nursing home patients demonstrated that 8% of 157 residents with diabetes had low glucose levels (defined as values below 60 mg/dl with or without symptoms and values 60 to 75 mg/dlwith usual hypoglycemic symptoms) when tested on a single evening.36 Based on this high prevalence, nocturnal glucose determinations are recommended by the authors as part of routine diabetic care in the nursing home--particularly for residents with dementia, previous episodes of hypoglycemia, recent changes in the medication regimen, or recent onset of infections.

Once hypoglycemia is diagnosed, prompt response is necessary to reduce the adverse consequences of this treatment. The use of 15 g to 20 g of carbohydrate in the form of glucose or sucrose tablets or solution is recommended. Glucose gel or orange juice appears to be less effective in treating hypoglycemia, according to one study.37 Glucagon is often given in more severe cases of hypoglycemia, but an exact blood glucose level for concern has not been determined. Often, there may be an overreaction to hypoglycemia with use of higher than necessarydoses of glucagon and large amounts of sucrose, with subsequent rebound hyperglycemia. In most studies, rapid provision of sucrose-containing substances combined with a sandwich or other snack containing protein is usually sufficient. The addition of the snacks prolongs the absorption of carbohydrate, ensuring that sufficient glucose is absorbed for the entire duration of hyperinsulinemia.

Diabetic Nonketotic Hyperosmolar State

This condition, which is predominantly a disease of the elderly, occurs much more commonly in nursing home residents with diabetes than in the general population. In one study, 18% of patients with this condition were nursing home residents.38 Understanding the underlying causes and pathophysiology is essential for appropriate treatment.39

Eye Complications

One of the most common causes of blindness in older adults is diabetic retinopathy. Annual eye examinations to detect retinopathy and other eye pathology are recommended for all patients who have diabetes mellitus. Studies of the efficacy of eye examinations in nursing homes are lacking. Studies of ambulatory older adult populations suggest that there are also potential benefits from improved diabetic control to retard the onset of retinopathy.40 Developing a monitoring and reminder system for regularly scheduled diabetic eye care should be a priority for medical directors.

Foot Care

Evaluation of the foot for skin breakdown is best accomplished by the patient's primary care provider and by registered nursing staff working in the nursing home. Although nurses' aides see the feet of patients more than any other providers, they are often not adequately trained to recognize foot problems. In-service training programs providing diabetic education for aides and nursing staff are recommended. These programs should emphasize early identification of podiatric problems.

Renal Disease

Diabetic nephropathy is the most-frequent cause of chronic renal failure in older adults. Good control of glucose as measured by hemoglobin A1c does appear to be associated with decreased risk of nephropathy, although the extent that normalization of glucose prevents this complication is not known. Optimizing antihypertensive therapy is important in delaying diabetic- related renal disease. The use of angiotensin-converting enzyme inhibitors even in the normotensive patient also appears to be associated with delayed proteinuria.

Vascular Disease

In addition to the microvascular complications listed above, diabetes is a strong risk factor for concomitant cardiac,41 cerebrovascular, and peripheral vascular disease. Concomitant hypercholesterolemia often significantly improves with better diabetic control. The use of aspirin as prophylaxis for cerebrovascular disease should be considered. Careful evaluation of any skin breakdown in patients with decreased peripheral pulsations should also be part of good comprehensive care of diabetic patients.

The question of whether persons with diabetes have more silent ischemia than other older populations has not yet been resolved. However, with the high prevalence of dementia in this population, other symptoms suggestive of these problems should raise suspicion about cardiac disease in these individuals.

Role of the Medical Director in Diabetes Management

Medical directors can have a major role in the management of this important problem. Evidence exists that both long-term care nurses and aides have inadequate knowledge in this important area.42 Facility medical directors can often serve as consultants for particularly difficult patient management issues. Knowledge of the basic principles of diabetic management--which are frequently overlooked in diabetic care--can be a successful adjunct to improved clinical outcomes. Looking at diabetes management as part of a continuum of chronic disease management can be especially useful for medical directors who have the time and inclination to participate in these types of activities. It is not uncommon for primary care providers in the nursing home to have to manage several acute issues on a regular basis and to forget the value of managing chronic illnesses. Development and oversight of protocols that are predominantly nurse-managed may result in significant improvement of care; however, data on this approach are lacking at this time.

One method to improve diabetic care is the use of standing orders approved by the primary care provider at the time of admission. Examples of possible orders are listed in TableII. The use of standing orders was found in one recent study to be associated with diabetic care practices that were more in line with national guidelines.43 In addition, modifications of standing orders may include notification of attending health care providers of plasma glucose levels above 200 mg/dl or less than 80 mg/dl. Ideally, a nurse with interest and skills in diabetic management within the facility can be designated to monitor diabetes management and control. Another option is to try to increase the knowledge level of nursing aides. A recent study, however, which included an intervention to improve general nursing home care by aides, increased knowledge but not performance.44

A more systematic approach to diabetic management can also be undertaken by explicitly determining responsibilities of health care team members and development of diabetic care protocols. One such approach that was used in a large predominantly skilled nursing facility resulted in a substantial improvement in the quality of diabetic care.45

Diabetes mellitus is a highly prevalent chronic illness in the nursing home. Because of the nature of the population in the nursing home, the goals of therapy are best matched to the subgroups of individuals residing in the facility, and treatment must be highly individualized. Developing a nursing homeú wide systemic approach to management of this disease will likely result in the best outcomes. Because of the high frequency of this illness in populations served by nursing homes, it is incumbent upon the medical director to provide leadership in this important area.

Annals of Long-Term Care - ISSN: 1524-7929 - Volume 6 - Issue 03 - March 1998