Geriatric Medicine/Metabolic Diseases

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Chapter 11: Metabolic Diseases[edit | edit source]

Objectives:

  • Discuss pharmacologic and non-pharmacologic treatments of metabolic diseases in geriatric patients
  • Describe appropriate lab values for diabetics in the geriatric population and deviations from expectations for younger patients
  • Describe the use of insulins and oral medications for treatment of diabetes in the geriatric population
  • Describe treatment of hypertension in the geriatric population and consequences of untreated hypertension
  • Describe pharmacologic methods of treating hyperlipidemia in the geriatric population

Diabetes in Geriatric Patients[edit | edit source]

Diabetes mellitus is a chronic condition that affects the way glucose is metabolized. Primarily among older adults, type 2 diabetes is the most common, and is characterized by (1) impaired fasting glucose and (2) impaired glucose tolerance due to decreased insulin sensitivity (i.e. increased insulin resistance). Treatment is both non-pharmacologic (weight loss, lifestyle modifications) and pharmacologic. The primary goal in maintaining glycemic control is to minimize long-term microvascular complications associated with the increased osmotic pressure due to increased glucose concentrations in the blood. However, as age increases, risk of developing these complications decreases due to onset of disease and life expectancy. Furthermore, hypoglycemia will have faster and more detrimental effects on older and frail patients compared to hyperglycemia. Therefore, tight glycemic control is not always appropriate. The choice of insulin replacement versus anti-hyperglycemic oral agents must be tailored to goals of care.

Diabetes mellitus control can be monitored by hemoglobin A1c testing. The test is typically performed every three months as this coincides with the lifespan of the erythrocyte (red blood cell) and the extent of glycosylation from the concentration of glucose in the blood, providing an average blood sugar over this period. For older adults, a hemoglobin A1c in the range of 7-9% (an average blood sugar range 152-212 mg/dL) is felt to be appropriate depending on functional status and location of care. Community-dwelling adults should be closer to 7%; long-term care residents may be maintained closer to 9%. (Sources will disagree over these numbers.) Goals must be individualized and tailored to individual patient care. Ideally, A1c values in both community-dwelling and long-term care residents will be above 5%.

Diabetes is diagnosed in adults if their hemoglobin A1c is greater than 6.5% or if a random blood sugar greater than 200 mg/dL; some flexibility with regard to initiation of treatment in older adults is warranted. Insulin sensitivity decreasing with age is part of normal aging physiology and occurs due to increasing adipose tissue (fat) and decreased muscular metabolism of glucose. Symptoms of prolonged hyperglycemia (typically >400 mg/dL) will include fatigue, polyuria, polydipsia, polyphagia, and weight loss, among others. Symptoms of hypoglycemia (typically <60 mg/dL) which are more acutely concerning than hyperglycemia include dizziness, weakness, confusion, diaphoresis, and delirium.

Pharmacologic treatment of diabetes, when warranted, include insulin (long-acting versus short-acting), metformin (depending on kidney function), sulfonylureas (which are known to precipitate hypoglycemia), thiazolidinediones (TZDs; known for exacerbating heart failure), and dipeptidyl peptidase-4 (DPP4) inhibitors. Insulin is sometimes underutilized in the elderly because of fear (by the physician, patient, or family) that it is too complicated or too dangerous. With the availability of long acting insulins, it has become easier to incorporate insulin with oral hypoglycemic medications in older patients who have suboptimal glycemic control. Insulin metabolism is altered in patients with chronic kidney disease, and less is required for adequate treatment.

Overview of diabetes medications:

Insulins (delivered subcutaneously):

  • rapid-acting: lispro, aspart - lasts 3-5 hours; given with meals to lower post-prandial glucose; taken 15 minutes before meals
  • short-acting: regular (R) - lasts for 5-8 hours; taken 30-60 minutes before meals
  • intermediate-acting: NPH - covers 18-24 hours; has fallen out of use due to long/short acting combination regimens
  • long-acting: glargine, detemir - lasts for ca. 24 hours
  • pre-mixed preparations are also available depending on physician preference


Metformin:

  • Mechanism: decreases hepatic gluconeogenesis
  • should be avoided in patients who have a serum creatinine of 1.5 mg/dL, regardless of sex
  • side effects include diarrhea and lactic acidosis
  • often available in a combination medication with other oral agents


Sulfonylureas:

  • Mechanism: bind to ATP-sensitive potassium channels on pancreatic beta cells, opening voltage-gated calcium channels increasing insulin release
  • most commonly used are glipizide and glimeperide
  • high incidence of hypoglycemia due to increased insulin production and release


Thiazolidinediones:

  • Mechanism: activate peroxisome proliferator-activated receptors (PPARs) to decrease amount of fatty acids in circulation, increasing need for glucose metabolism to provide energy for cellular processes
  • common examples include pioglitazone; rosiglitazone was withdrawn from the market for a time but is again available
  • known side effects include lower extremity edema and exacerbation of congestive heart failure


Dipeptidyl peptidase-4 (DPP4) inhibitors:

  • Mechanism: work by reducing glucagon and blood glucose levels due to increased incretin leading to increased insulin secretion and decreased gastric emptying
  • common examples include linagliptin and sitagliptin


Other concerns for diabetics include hepatitis B vaccination status (check serum hepatitis B surface antibody reactivity), monitoring lipid panels due to diabetes being a coronary artery disease risk equivalent, vision screening (retinopathy), and foot care (neuropathy and peripheral vascular disease).

Hypertension in Geriatric Patients[edit | edit source]

Hypertension occurs when the force of the blood against the walls of the arteries is increased beyond acceptable range. With increasing age, there is increased thickness of arterial intima and media. The net result of this is increased vascular stiffness, leading to increased acceptable blood pressures of 150 mm Hg for systolic blood pressures compared to 140 mm Hg for younger adults. Diastolic blood pressures should be maintained under 90 mm Hg regardless of age. Medications known to increase blood pressure, as discussed in previous chapters, include corticosteroids, NSAIDs, and others.

Treatment as recommended by the JNC8 guidelines include starting with any one of thiazide diuretics, angiotensin-converting enzyme inhibitors (ACE inhibitors), angiotensin receptor blockers (ARBs), or calcium-channel blockers (CCBs). Aggressive therapy is not appropriate if adverse side effects (such as orthostatic hypotension) cannot be avoided. Chapter 10 discusses syncope and hypotension.

Complications of untreated chronic hypertension include hypertensive heart disease (chronic systolic/chronic diastolic heart failure), hypertensive kidney disease, (chronic kidney disease), and cerebrovascular disease (CVAs/TIAs), among others.

Hyperlipidemia in Geriatric Patients[edit | edit source]

Hyperlipidemia is the abnormal elevation of lipids in the blood. Four quantities of interest measured in a lipid panel include total cholesterol (TC), triglycerides (TG), high-density lipoprotein (HDL), and low-density lipoprotein (LDL). LDL is calculated and not directly measured: LDL(calc) = TC – TG/5 – HDL

Lipid panels are ordered fasting due to the effect of food metabolism on triglycerides; however, a non-fasting lipid panel should provide accurate insight into lipid control with the exception of the triglyceride level. Ideally, TC should be less than 200 mg/dL, TG should be less than 150 mg/dL, HDL should be greater than 40 mg/dL, and LDL(calc) should be less than 70 mg/dL. However, "treating to a number" has fallen out of favor, replaced by the 10-year-risk score of atherosclerotic cardiovascular disease score. An example of the ASCVD calculator can be found at here with scoring guidelines. Coronary artery disease and hyperlipidemia show a direct proportionality, however: low HDL and high LDL show increased incidence. Frail older adults often have decreased cholesterol levels. As such, lipid-lowering medications should not be prescribed to patients with a limited life expectancy.

Treatment of hyperlipidemia involves lifestyle modifications and pharmacologic treatment. Pharmacologic treatment of hyperlipidemia involves the use of bile-acid binding resins (cholestyramine), ezetimibe, fibrates (gemfibrozil), HMG-CoA reductase inhibitors (statins), niacin, and omega-3 fatty acids. First-line treatment of hyperlipidemia should be accomplished with statins. While, arguably, niacin and fibrates will show better effects for the lowering of triglycerides, statins show improvement in TG, HDL, and LDL levels. Statins are associated with myopathic pain, especially with higher intensity. Higher intensity statins are indicated for coronary artery disease with myocardial infarction and cerebrovascular disease with TIA/CVA events. Pravastatin has shown the least incidence of myopathic pain. Statin equivalency charts are available which provide conversion between one statin to another should intolerance become an issue. The ATP III guidelines provide a useful comparison of agents and their effectiveness. A statin equivalency chart is available for reference.

Review Questions[edit | edit source]

Questions 1-2: A 72-year-old female presents to her primary care physician for follow up of her chronic medical conditions. Her past medical history is notable for hypertension, hyperlipidemia, and diabetes mellitus type 2. She currently takes glipizide, lisinopril, and atorvastatin.; Her hepatitis B surface antibody is non-reactive. Her most recent hemoglobin A1c was 7.2%. She denies any new problems or complaints. Her mentation is at its baseline. Her son who is with her for the visit has no concerns at present. Her vital signs and physical exam are unremarkable.

1. Compared to the ambulatory community, what is an optimal hemoglobin A1c in a long-term care resident?

A. Less than 5%.
B. Less than 6%.
C. Less than 7%.
D. Less than 8%.
E. Less than 9%.

2. Why is an acceptable blood pressure 150/90 in persons aged 65 and older?

A. Decreased compliance of arterial blood vessels.
B. Increased compliance of arterial blood vessels.
C. Decreased compliance of the left ventricle.
D. Increased compliance of the left ventricle.

Answers to Review Questions[edit | edit source]

  1. E - Hemoglobin A1c is a measure of blood sugar control over a three-month period. Blood sugar control is a predictor of long-term complications in a diabetic patient. In the long-term care elderly population, hypoglycemia is more of a concern than tight glycemic control. Therefore, an optimal A1c should be less than 9% (and ideally above 5%).
  2. A - Compliance of arterial blood vessels decreases with aging.