Acute Complications of Diabetes
There are three major acute complications of diabetes related to short-term imbalances in blood glucose levels: hypoglycemia, DKA, and HHNS, which is also called hyperglycemic hyperosmolar non-ketotic coma or hyperglycemic hyperosmolar syndrome.
HYPOGLYCEMIA (INSULIN REACTIONS)
Hypoglycemia (abnormally low blood glucose level) occurs when the blood glucose falls to less than 50 to 60 mg/dL (2.7 to 3.3 mmol/L). It can be caused by too much insulin or oral hypo-glycemic agents, too little food, or excessive physical activity. Hy-poglycemia may occur at any time of the day or night. It often occurs before meals, especially if meals are delayed or snacks are omitted. For example, midmorning hypoglycemia may occur when the morning regular insulin is peaking, whereas hypo-glycemia that occurs in the late afternoon coincides with the peak of the morning NPH or Lente insulin. Middle-of-the-night hypo-glycemia may occur because of peaking evening or predinnerNPH or Lente insulins, especially in patients who have not eaten a bedtime snack.
The clinical manifestations of hypoglycemia may be grouped into two categories: adrenergic symptoms and central nervous system (CNS) symptoms. In mild hypoglycemia, as the blood glucose level falls, the sympathetic nervous system is stimulated, resulting in a surge of epinephrine and norepinephrine. This causes symp-toms such as sweating, tremor, tachycardia, palpitation, nervous-ness, and hunger.
In moderate hypoglycemia, the fall in blood glucose level de-prives the brain cells of needed fuel for functioning. Signs of im-paired function of the CNS may include inability to concentrate, headache, lightheadedness, confusion, memory lapses, numbness of the lips and tongue, slurred speech, impaired coordination, emotional changes, irrational or combative behavior, double vision, and drowsiness. Any combination of these symptoms (in addi-tion to adrenergic symptoms) may occur with moderate hypo-glycemia.
In severe hypoglycemia, CNS function is so impaired that the patient needs the assistance of another person for treatment of hypo-glycemia. Symptoms may include disoriented behavior, seizures, difficulty arousing from sleep, or loss of consciousness
Hypoglycemic symptoms can occur suddenly and unexpectedly. The combination of symptoms varies considerably from person to person. To some degree, this may be related to the actual level to which the blood glucose drops or to the rate at which it is drop-ping. For example, patients who usually have a blood glucose level in the hyperglycemic range (eg, in the 200s or greater) may feel hypoglycemic (adrenergic) symptoms when their blood glu-cose quickly drops to 120 mg/dL (6.6 mmol/L) or less. Con-versely, patients who frequently have a glucose level in the low range of normal may be asymptomatic when the blood glucose slowly falls to less than 50 mg/dL (2.7 mmol/L).
Another factor contributing to altered hypoglycemic symp-toms is a decreased hormonal (adrenergic) response to hypo-glycemia. This occurs in some patients who have had diabetes for many years. It may be related to one of the chronic diabetic com-plications, autonomic neuropathy. As the blood glucose level falls, the normal surge in adrenalin does not occur. The patient does not feel the usual adrenergic symptoms, such as sweating and shakiness. The hypoglycemia may not be detected until moder-ate or severe CNS impairment occurs. These patients must per-form SMBG on a frequent regular basis, especially before driving or engaging in other potentially dangerous activities.
In the elderly diabetic patient, hypoglycemia is a particular con-cern for many reasons:
• Elderly people frequently live alone and may not recognize the symptoms of hypoglycemia.
• With decreasing renal function, it takes longer for oral hypoglycemic agents to be excreted by the kidneys.
• Skipping meals may occur because of decreased appetite or financial limitations.
• Decreased visual acuity may lead to errors in insulin administration.
Immediate treatment must be given when hypoglycemia occurs. The usual recommendation is for 15 g of a fast-acting concen-trated source of carbohydrate such as the following, given orally:
• Three or four commercially prepared glucose tablets
• 4 to 6 oz of fruit juice or regular soda
• 6 to 10 Life Savers or other hard candies
• 2 to 3 teaspoons of sugar or honey
It is not necessary to add sugar to juice, even if it is labeled as unsweetened juice: the fruit sugar in juice contains enough carbo-hydrate to raise the blood glucose level. Adding table sugar to juice may cause a sharp increase in the blood glucose level, and the patient may experience hyperglycemia for hours after treatment.
The blood glucose level should be retested in 15 minutes and retreated if it is less than 70 to 75 mg/dL (3.8 to 4 mmol/L). If the symptoms persist more than 10 to 15 minutes after initial treatment, the treatment is repeated even if blood glucose testing is not possible. Once the symptoms resolve, a snack containing protein and starch (eg, milk or cheese and crackers) is recom-mended unless the patient plans to eat a regular meal or snack within 30 to 60 minutes.
It is important for patients with diabetes, especially those receiv-ing insulin, to learn that they must carry some form of simple sugar with them at all times (ADA, Insulin Administration, 2002). There are many different commercially prepared glucose tablets and gels that patients may find convenient to carry. If the patient has a hypoglycemic reaction and does not have any of the recommended emergency foods available, any available food (preferably a carbohydrate food) should be eaten.
Patients are advised to refrain from eating high-calorie, high-fat dessert foods (eg, cookies, cakes, doughnuts, ice cream) to treat hypoglycemia. The high fat content of these foods may slow the absorption of the glucose, and the hypoglycemic symptoms may not resolve as quickly as they would with the intake of car-bohydrates. The patient may subsequently eat more of the foods when symptoms do not resolve rapidly. This in turn may cause very high blood glucose levels for several hours after the reaction and may also contribute to weight gain.
Patients who feel unduly restricted by their meal plan may view hypoglycemic episodes as a time to reward themselves with desserts. It may be more prudent to teach these patients to incorporate occasional desserts into the meal plan. This may make it easier for them to limit their treatment of hypoglycemic episodes to simple (low-calorie) carbohydrates such as juice or glucose tablets.
For patients who are unconscious and cannot swallow, an injec-tion of glucagon 1 mg can be administered either subcutaneously or intramuscularly. Glucagon is a hormone produced by the alpha cells of the pancreas that stimulates the liver to release glu-cose (through the breakdown of glycogen, the stored glucose). In-jectable glucagon is packaged as a powder in 1-mg vials and must be mixed with a diluent before being injected. After injection of glucagon, it may take up to 20 minutes for the patient to regain consciousness. A concentrated source of carbohydrate followed by a snack should be given to the patient on awakening to prevent recurrence of hypoglycemia (because the duration of the ac-tion of 1 mg of glucagon is brief [its onset is 8 to 10 minutes and its action lasts 12 to 27 minutes]) and to replenish liver stores of glucose. Some patients experience nausea after the administration of glucagon; if this occurs, the patient should be turned to the side to prevent aspiration. The patient should be instructed to notify the physician after severe hypoglycemia has occurred.
Glucagon is sold by prescription only and should be part of the emergency supplies kept available by patients with diabetes who require insulin. Family members, neighbors, or coworkers should be instructed in the use of glucagon. This is especially true for patients who receive little or no warning of hypoglycemic episodes.
In the hospital or emergency department, patients who are un-conscious or cannot swallow may be treated with 25 to 50 mL 50% dextrose in water (D50W) administered intravenously. The effect is usually seen within minutes. Patients may complain of a headache and of pain at the injection site. Assuring patency of the intravenous (IV) line used for injection of 50% dextrose is essen-tial because hypertonic solutions such as 50% dextrose are very irritating to the vein.
Hypoglycemia is prevented by aconsistent pattern of eating, administering insulin, and exercis-ing. Between-meal and bedtime snacks may be needed to coun-teract the maximum insulin effect. In general, the patient should cover the time of peak activity of insulin by eating a snack and by taking additional food when physical activity is increased. Rou-tine blood glucose tests are performed so that changing insulin re-quirements may be anticipated and the dosage adjusted. Because unexpected hypoglycemia may occur, all patients treated with in-sulin should wear an identification bracelet or tag stating that they have diabetes.
Patients and family members must be instructed about the symptoms of hypoglycemia. Family members in particular must be made aware that any subtle (but unusual) change in behavior may be an indication of hypoglycemia. They should be taught to encourage and even insist that the person with diabetes assess blood glucose levels if hypoglycemia is suspected. Some patients (when hypoglycemic) become very resistant to testing or eating and become angry at family members trying to treat the hypo-glycemia. Family members must be taught to persevere and to understand that the hypoglycemia can cause irrational behavior.
Some patients with autonomic neuropathy or those taking beta blockers such as propranolol to treat hypertension or cardiac dysrhythmias may not experience the typical symptoms of hypo-glycemia. It is very important for these patients to perform blood glucose tests on a frequent and regular basis. Patients who have type 2 diabetes and who take oral sulfonylurea agents may also develop hypoglycemia (especially those taking chlorpropamide, a long-lasting oral hypoglycemic agent).
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