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COMPLICATIONS OF DIABETES IN OLDER PERSONS:
Acute metabolic complications:
Both diabetic ketoacidosis (DKA) and hyper-osmolar non-ketotic coma (HONK) can be seen in the elderly. DKA is rare and its features and management do not differ from those in younger diabetics, but its mortality is greatest in old age, particularly because of associated cardiovascular disease.
HONK almost always occurs in older people, and half the time DM has not been previously diagnosed or treated. The tendency of the elderly to develop HONK can be explained by a combination of impaired maintenance of serum osmolality, decreased thirst perception, and decreased access to water, especially in the bed-ridden, dependant patient in the setting of multiple medical problems. Reduced thirst perception renders the polydipsia less dramatic, thereby lessening recognition by self or others, ending in hyperosmolar coma.
An acute infection is the most frequent predisposing factor (40 - 60%), with pneumonia being the most common infection. Other illnesses such as stroke, acute myocardial infarction, renal insufficiency, and medications such as glucocorticoids can also be predisposing factors.
Patients typically present with an altered sensorium, profound dehydration, and sometimes cardiovascular collapse. Focal neurological deficits, seizures, and central neurogenic hyperthermia that resolve with treatment can also be present. Leucocytosis is characteristic with counts up to 50,000 cells/mm3 even in the absence of infection.
The treatment of HONK involves frequent and careful monitoring. Although 4 - 6 liters of fluid may be needed in the first 12 hours, such rapid replacement may not be feasible in the older persons, who often exhibit poor cardiac reserve. In most cases, insulin and IV fluids can be safely started simultaneously. The exceptions are patients with hypokalemia or hypotension, to whom IV fluids should be given before insulin to prevent the worsening of hypokalemia or hypotension, which can occur in response to insulin and the resulting intracellular shift of glucose, potassium, and water.
As a general rule, 0.1 unit of regular insulin per kilogram of body weight is given as an IV bolus, followed by an infusion of regular insulin at 0.1 U/kg/hr until blood glucose levels reach 14 mmol/L. At this time, dextrose is added to the IV fluids and insulin infusion is decreased to 0.05 U/kg/hr. A decline in blood glucose of about 10% of the baseline value per hour is a reasonable goal in the elderly. Careful attention should be given to potassium replacement.
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