Diabetes and Thyroid Disorders in the Elderly
Sara E. Young
Richelle J. Koopman
Arch G. Mainous III
CLINICAL PEARLS
Healthy elderly patients with diabetes should be encouraged to achieve the same glycemic, lipid, and blood pressure goals as younger patients.
Elderly patients with diabetes mellitus are at increased risk for cardiovascular disease.
Diet, exercise, and pharmacologic therapy recommendations for elderly patients with diabetes must be made in the context of decreased functional status, comorbidity, and polypharmacy.
Use of angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs) should be considered for individuals with diabetes with evidence of microalbuminuria and/or hypertension.
Depression is a common comorbid condition of diabetes and unrecognized depression can interfere with diabetes care in older patients.
With normal aging, the thyroid gland becomes more nodular, with 90% of women over age 80 having nodules.
Subclinical hypothyroidism becomes increasingly common in older women.
Amiodarone can precipitate hyperthyroidism, although hypothyroidism is more common.
Cardiac disease is an important consideration in the treatment of older patients with hypo- or hyperthyroidism.
Symptoms of thyroid disease are subtle and may mimic other diseases in older populations with multiple medical problems.
Endocrine disease is common in the elderly. Recent estimates suggest that at least 20% of patients over the age of 65 have diabetes. Elderly patients with diabetes have higher rates of premature death, functional disability, and
comorbid illnesses such as hypertension, congestive heart disease, and stroke compared to those without diabetes. Similarly, thyroid disease in the elderly is approximately twice that in younger individuals. Because of the morbidity associated with thyroid disease, the U.S. Preventive Services Task Force suggests that clinicians should be aware of subtle signs of thyroid dysfunction in the elderly.
comorbid illnesses such as hypertension, congestive heart disease, and stroke compared to those without diabetes. Similarly, thyroid disease in the elderly is approximately twice that in younger individuals. Because of the morbidity associated with thyroid disease, the U.S. Preventive Services Task Force suggests that clinicians should be aware of subtle signs of thyroid dysfunction in the elderly.
Some characteristics of aging complicate diagnosis and management. Elderly patients with hypothyroidism are more likely than younger patients to present with cardiovascular symptoms or neurologic findings, thereby contributing to difficulties in diagnosis. With aging, lean body mass decreases and body fat increases, whereas decreased physical activity is common, all of which play a role in insulin resistance. Because elderly patients often have multiple diseases and take many medications that often mimic or mask the usual presentation of endocrine disease, diagnosis and management become more complex. Moreover, the care of older adults with diabetes and thyroid disease is complicated by their clinical and functional heterogeneity.
DIFFERENTIAL DIAGNOSIS
The differential diagnosis of endocrine disorders is discussed in Table 33.1.
CASE ONE
Mrs. M. is a 68-year-old who comes to your office for follow-up of hypertension. She is obese and has not lost weight despite your advice on diet and exercise at her last visit. She complains of fatigue over the last 2 months. On further questioning, she has noted blurring of vision and vaginal itching without polyuria. She has a blood pressure of 142/93 mm Hg and a normal examination except for vaginal candidiasis. You order a fasting plasma glucose, which is 148 mg per dL. A second fasting plasma glucose of 164 mg per dL confirms your suspicions that Mrs. M. has developed diabetes mellitus.
TYPE 2 DIABETES MELLITUS
Description/Definition of Problem
Type 2 diabetes mellitus is a common, potentially debilitating condition characterized by hyperglycemia and insulin resistance. The discussion is limited to type 2 diabetes because type 1 diabetes, although important, is not commonly seen in the geriatric population.
Pathophysiology
Type 2 diabetes is largely a defect of the action of insulin at the level of the cell. The disease is characterized by high levels of circulating insulin and relative resistance to the action of insulin. Obesity plays an important role in the development of type 2 diabetes; obesity itself, and especially obesity in the abdominal region, leads to some degree of insulin resistance. β-Cell destruction and ketoacidosis are not prominent features of type 2 diabetes. Ketoacidosis in the elderly patient with hyperglycemia should initiate a search for other causes of acidosis, such as lactic acidosis when used with metformin.
TABLE 33.1 PARTIAL LIST OF ENDOCRINE DISORDERS (ICD-9) | |||||||||||||||||||||||||||||||||||||||||
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Prior to the onset of clinical diabetes, patients may be diagnosed with one of the two defined prediabetes conditions: Impaired fasting glucose (IFG) and impaired
glucose tolerance (IGT). IFG is defined as a fasting plasma glucose from 100 mg per dL (5.6 mmol per L) to 125 mg per dL (6.9 mmol per L). IGT is defined as a 2-hour plasma glucose from 140 mg per dL (7.8 mmol per L) to 199 mg per dL (11.0 mmol per L) in the course of a glucose tolerance test.1 People with insulin resistance are at approximately a fivefold risk for diabetes, but this risk can be modified by modest weight loss and lifestyle modifications.
glucose tolerance (IGT). IFG is defined as a fasting plasma glucose from 100 mg per dL (5.6 mmol per L) to 125 mg per dL (6.9 mmol per L). IGT is defined as a 2-hour plasma glucose from 140 mg per dL (7.8 mmol per L) to 199 mg per dL (11.0 mmol per L) in the course of a glucose tolerance test.1 People with insulin resistance are at approximately a fivefold risk for diabetes, but this risk can be modified by modest weight loss and lifestyle modifications.
Systems Impacted
Elderly patients are at risk for many of the long-term complications of type 2 diabetes including cardiovascular disease (CVD), nephropathy and end-stage renal disease, peripheral vascular disease, neuropathy, and retinopathy and blindness. CVD is the primary cause of morbidity and mortality for patients with type 2 diabetes. In addition to being an independent risk factor for CVD, diabetes also tends to coexist with other risk factors for CVD, specifically hypertension and hyperlipidemia. When combined with the decreased sensation of diabetic neuropathy, the poor healing associated with peripheral vascular disease puts the elderly person with diabetes at a 10-fold risk for amputation.
These complications of type 2 diabetes have important consequences for the geriatric patient. Activities of daily living can be severely impacted by decreased exercise tolerance associated with heart disease. Joint deformity and amputation associated with peripheral neuropathy and peripheral vascular disease can further limit mobility as well as stability of gait. Additionally, the decreased visual sensation of retinopathy and decreased peripheral sensation of neuropathy may isolate the elderly patient and pose important safety risks, including falls. Poor vision, the result of diabetic retinopathy, may also complicate the ability to read medication bottles, read blood glucose meters, or correctly use insulin injections.
Type 2 diabetes has also been linked to cognitive decline in older persons. The changes in functional and cognitive status of the older patient must be assessed and integrated into the management plan. Urinary incontinence is also an important consequence of diabetes in older persons. Urinary incontinence may be multifactorial in its origin and the clinician should consider the contributions of polyuria associated with poor glycemic control, neurogenic bladder, cystocele and atrophic vaginitis in women, urinary tract infections, and vaginal candidiasis associated with poor glycemic control.
Older persons are at greater risk than younger persons with type 2 diabetes for nonketotic hyperglycemic-hyperosmolar coma. This dangerous and potentially life-threatening complication is largely the result of uncontrolled hyperglycemia in combination with inadequate fluid intake. Neglected or undiagnosed diabetes may be an important factor in the development of this complication, but infection or newly prescribed drugs that affect glucose tolerance can also be predisposing factors, especially for elders who live alone or in institutional settings.
Prevalence
Type 2 diabetes is equally prevalent in men and women. The risk for type 2 diabetes increases with age. The combined prevalence of diagnosed type 1 and type 2 diabetes among those aged 60 and older increased from 12.7% (1988 to 1994) to 15.2% (1999 to 2000).2 Undiagnosed diabetes was estimated to affect an additional 4.2% of Americans aged 60 and older during 1999 to 2000; an additional 14.6% had IFG.3
Genetics
A family history of type 2 diabetes is a risk factor for the development of diabetes. Currently it is thought that there are many different causes of type 2 diabetes, and its genetic basis is likely also multifactorial.
Signs and Symptoms
Type 2 diabetes tends to progress from an asymptomatic stage to overt symptoms. However, when symptoms do begin to occur, they may be vague and nonspecific and, therefore, may not trigger recognition in either the patient or their physician. Hyperglycemia results in a catabolic state that may cause weight loss and fatigue. Patients may also experience the classic “polys” of polydipsia, polyuria, and polyphagia, although these symptoms also may be subtle. Prolonged hyperglycemia may also result in increased susceptibility to infection, including both bacterial and monilial skin infections, and vaginal candidiasis in women.
Course/Timeline
Type 2 diabetes typically has an insidious onset, with a prolonged preclinical period before the disease is detected. The time from onset of type 2 diabetes to clinical diagnosis has been estimated to last an average of 9 to 12 years. Additionally, patients likely pass from normal glucose tolerance through several years in the prediabetic states of IGT and IFG and on to type 2 diabetes.
Complications of type 2 diabetes accrue with the duration of the disease, although their development can have quite a variable course. In general, diabetes needs to be present for approximately 10 years before patients begin to have its complications. However, because there may be a delay of diagnosis for many years, in certain cases, complications may begin to appear soon after diagnosis.
Risk Factors
There are a variety of risk factors for type 2 diabetes. The major risk factors for type 2 diabetes that have been suggested for clinicians by the American Diabetes Association (ADA) are the following:1
Age ≥45 years
Overweight (BMI ≥25 kg per m2)
Family history of diabetes in a parent or sibling
Habitual physical inactivity
Race/ethnicity (nonwhite)
Previously identified IFG or IGT
History of gestational diabetes mellitus of delivery of a baby weighing >9 lbs
Hypertension (≥140/90 mmHg)
High-density lipoprotein (HDL) cholesterol ≤35 mg per dL (0.90 mmol per L)
Triglyceride level ≥250 mg per dL
Polycystic ovary syndrome
History of vascular disease
Workup/Keys to Diagnosis
Physical Examination
The physical examination for diagnosing diabetes and ongoing management should include the following:1
Height and weight measurement
Blood pressure determination and orthostatic measurements, when indicated
Funduscopic examination
Oral examination
Thyroid palpation
Cardiac examination
Abdominal examination (e.g., for hepatomegaly)
Evaluation of pulses by palpation and with auscultation
Hand and finger examination
Foot examination
Skin examination (for acanthosis nigricans and insulininjection sites)
Neurologic examination
Signs of diseases that can cause secondary diabetes (e.g., hemochromatosis, pancreatic disease).
Management
Ongoing Management
For established elderly patients with type 2 diabetes, the management plan should be formulated as an individualized therapeutic alliance among the patient and family, the physician, and other members of the health care team. Any plan should recognize diabetes self-management education as an integral component of care. Treatment goals are to prevent metabolic decompensation and control factors that contribute to the high risk of cardiovascular complications in the elderly patient with diabetes. Control of hyperglycemia and identifying and controlling hypertension, lipid disorders, and smoking are all important goals in a diabetes care plan for the elderly patient. Long-term treatment plans must consider the individual patient’s remaining life expectancy, existing diabetes complications, coexisting medical and neuropsychiatric disorders, and the ability and commitment of the patient and the caregiver to adhere to the proposed, often complex, treatment plan. Elderly persons are at increased risk for adverse effects related to all aspects of treatment including diet, exercise, and medication (see Table 33.3).4,5
TABLE 33.2 BIOCHEMICAL CRITERIA (VENOUS PLASMA) FOR THE DIAGNOSIS OF DIABETES, IMPAIRED GLUCOSE TOLERANCE, AND IMPAIRED FASTING GLUCOSE | |||||||||||||||||
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Glycemic control is critical to managing patients with type 2 diabetes. The UK Prospective Diabetes Study (UKPDS) showed the benefits of intensive glycemic control for preventing or delaying the development and progression of long-term complications. The UKPDS, the largest and longest interventional trial conducted in patients with type 2 diabetes, conclusively showed the significant benefits of improving glycemic control with intensive treatment using insulin, sulfonylurea, or metformin.6 Epidemiologic analysis of 10-year UKPDS data showed a continuous relationship between the risk of microvascular complications and glycemia, such that for every 1 percentage point reduction in HbAIc there was a 37% reduction in the risk of microvascular complications.7 The major barrier for the implementation of intensive glycemic control, from both the physician’s and the patient’s perspectives, is the increased incidence of hypoglycemia.
Severe hyperglycemia produces excessive fatty acid mobilization and oxidation, muscle wasting by excessive protein catabolism, excessive glucose production, and loss of glucose in the urine. Precipitating factors include infection, pancreatitis, myocardial infarction (MI), dehydration, cerebrovascular accident, and alcohol abuse. Commonly used medications that can cause hyperglycemia include corticosteroids, β-blockers, β-agonists, thiazides, furosemide, antipsychotic agents, phenothiazines, thyroid hormone preparations, calcium channel blockers, estrogen, phenytoin, gemesterol acetate, opiates, and nicotinic acid.
TABLE 33.3 ONGOING MANAGEMENT GOALS AND RECOMMENDED FREQUENCY OF TESTING AMONG PATIENTS WITH TYPE 2 DIABETES | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Risk factors for developing hypoglycemia include advanced age, inconsistent caloric intake, high doses of insulin, delay in eating meal after administration of rapidacting insulin, and hypoglycemia unawareness.8
Cardiovascular Disease
CVD is the leading cause of mortality in individuals with diabetes. Studies have shown the efficacy of reducing cardiovascular risk factors in preventing or slowing CVD. Emphasis should be placed on reducing cardiovascular risk factors, when possible, and clinicians should be alert for signs and symptoms of atherosclerosis. A risk factor—based approach should be used in the initial diagnostic evaluation and follow-up to identify coronary heart disease (CHD) in asymptomatic diabetic patients. At least annually, cardiovascular risk factors (dyslipidemia, hypertension, smoking, family history of premature coronary disease, and presence of micro- or macroalbuminuria) should be assessed. Diagnostic cardiac stress testing is indicated in patients with typical or atypical cardiac symptoms and an abnormal resting electrocardiogram (ECG). Screening cardiac stress testing should be considered in those with a history of peripheral or carotid occlusive disease, those with a sedentary lifestyle who plan to begin a vigorous exercise program, and those with two or more of the risk factors noted in the preceding text.
Recommendations
In patients with congestive heart failure (CHF), metformin is contraindicated. The thiazolidinediones are associated with fluid retention and can complicate management of CHF1 (Evidence Level C).
An angiotensin-converting enzyme (ACE) inhibitor should be considered in patients older than 55 years with another cardiovascular risk factor to reduce the risk of cardiovascular events1 (Evidence Level A).
β-Blockers should be considered in patients with a prior MI or in patients undergoing major surgery to reduce mortality1 (Evidence Level A).
Peripheral Arterial Disease
Signs and symptoms suggestive of peripheral arterial disease include cold feet, atrophy of subcutaneous tissues, hair loss, intermittent claudication, and decreased or absent
dorsalis pedis and posterior tibial pulses. Ankle-brachial index (ABI)/Doppler pressures at the ankle and toes should be obtained when concern for ischemic change in the forefoot arises on the basis of history and physical examination. Refer patients with significant claudication or a positive ABI for further vascular assessment.
dorsalis pedis and posterior tibial pulses. Ankle-brachial index (ABI)/Doppler pressures at the ankle and toes should be obtained when concern for ischemic change in the forefoot arises on the basis of history and physical examination. Refer patients with significant claudication or a positive ABI for further vascular assessment.
Recommendation
Initial treatment recommendations involve behavior changes that include stopping smoking and a monitored program of physical activity; other management considerations include medications and surgical options1 (Evidence Level C).
Retinopathy
Up to 21% of patients with type 2 diabetes have retinopathy at the time of first diagnosis of diabetes, and most develop some degree of retinopathy over time. Other common age-related eye disorders, such as glaucoma, cataract, and macular degeneration, are also more common among individuals with diabetes. The duration of diabetes is probably the strongest predictor for development and progression of retinopathy, an important cause of blindness. Diabetic retinopathy has few visual or ophthalmic symptoms until visual loss develops. The protective effects of glycemic control and blood pressure control on development and progression of retinopathy has been confirmed for patients with type 2 diabetes. Epidemiologic analysis of 10-year UKPDS data showed a continuous relationship between the risk of microvascular complications and glycemia, such that for every 1% reduction in HbAIc there was a 37% reduction in the risk of microvascular complications.7 Aspirin therapy does not prevent retinopathy or increase the risk of hemorrhage. Laser photocoagulation can reduce the risk of vision loss in patients with proliferative changes.
Recommendations
Patients should have an initial dilated and comprehensive eye examination by an ophthalmologist experienced in diagnosis and management of diabetic retinopathy shortly after diabetes diagnosis1 (Evidence Level B).
Ophthalmic examinations for retinopathy should be repeated annually. If the patient has ophthalmic symptoms, established retinopathy, glaucoma, cataracts, AIc >8.0%, type 1 diabetes, or blood pressure >140/80 mmHg with abnormal findings, more frequent follow-up may be needed. Persons who are at lower risk may be examined every 2 years1 (Evidence Level B).
Nephropathy
Diabetic nephropathy occurs in 20% to 40% of patients with diabetes and is the leading cause of end-stage renal disease. Persistent microalbuminuria is a marker for development of nephropathy in type 2 diabetes. Random spot urine collection, measuring the albumin-to-creatinine ratio, is the preferred screening method for microalbuminuria. Microalbuminuria is diagnosed when at least two out of three tests measured within a 6-month period show levels of 30 to 299 μg per mg creatinine. Urinary albumin excretion over baseline values may occur with: Exercise within 24 hours, infection, fever, CHF, marked hyperglycemia, or marked hypertension. Glomerular filtration rate (GFR) is already affected by aging, and various calculation methods appear to be more accurate than creatinine clearance measured from 24-hour urine samples at predicting GFR. Standard formulas include the Cockcroft-Gault equation and the Levey equation. ACE inhibitors and angiotensin II receptor blockers (ARBs) have been shown to delay the progression to macroalbuminuria and delay the progression to nephropathy in patients with type 2 diabetes, hypertension, and microalbuminuria. Nutrition deficiency may occur in some individuals and lead to muscle weakness. Proteinrestricted meal plans should be designed by a registered dietitian. Radiocontrast media are particularly nephrotoxic in patients with diabetic nephropathy, and azotemic patients should be carefully hydrated before receiving any contrast.
Recommendations
All patients with type 2 diabetes should be screened for microalbuminuria at diagnosis and annually thereafter1 (Evidence Level C).
ACE inhibitors or ARBs should be used in the treatment of both micro- and macroalbuminuria (Evidence Level A); if one class is not tolerated then the other should be given a trial1 (Evidence Level C).
If ACE inhibitors, ARBs, or diuretics are used, monitor serum potassium levels for the development of hyperkalemia1 (Evidence Level B).
Consider referral to a physician experienced in the care of diabetic renal disease when the GFR has fallen to <60 mL/minute/1.73 m2, or if difficulties occur in the management of hypertension or hyperkalemia1 (Evidence Level B).
Optimize glucose and blood pressure control to reduce the risk and slow the progression of nephropathy1 (Evidence Level A).
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