Many patients will ultimately require insulin due to the progressive loss of beta-cell function that occurs in advanced diabetes. Starting insulin therapy early on in the disease may actually restore beta-cell function and reduce glucotoxicity.24 In elderly patients with uncontrolled diabetes, early treatment with basal insulin results in better glycemic control and less hypoglycemia than continuing to titrate oral agents.25
Despite these benefits, however, insulin use often is not optimized in the elderly due to concerns about hypoglycemia and difficulty of administration. Safe use of insulin requires careful selection of an appropriate insulin regimen, since insulin use has been identified as an independent predictor of severe hypoglycemia in the elderly.8,26 Before initiating insulin therapy, evaluate whether an older patient is cognitively and physically able to safely use insulin.
Multiple daily injections may be challenging for some older adults. Limit such insulin regimens to use in high-functioning patients. Although all types of insulin can cause hypoglycemia, regimens that mimic insulin’s normal physiologic pattern introduce less hypoglycemic risk. Using basal insulin that mimics the body’s sustained insulin level throughout the day is associated with a lower frequency of hypoglycemia in older people with diabetes than conventional insulin regimens. Long-acting insulins such as glargine, detemir, and degludec offer a lower risk of hypoglycemia, particularly nocturnal hypoglycemia which may contribute to falls.2,27
Neutral protamine Hagedorn insulin and regular insulin are not recommended for use in the elderly, as they do not mimic the body’s natural basal-bolus insulin production and thus put patients at higher risk of hypoglycemia.4 If insulin intensification is needed after optimizing basal insulin, consider adding mealtime insulin with a bolus of rapid-acting insulin (insulin aspart, insulin lispro, or insulin glulisine). It is important to note that the kidneys are responsible for 30% to 80% of insulin clearance from the body.28 Because insulin action is prolonged in renal insufficiency, prevent hypoglycemia by decreasing basal and bolus doses when the eGFR is below 50 mL/min/1.73m2.28
Dosing errors. Whenever possible, use insulin preparations that minimize dosing errors. Insulin pen formulations, if financially feasible, allow more accurate dosing and are more acceptable to older patients compared with syringes and vials.29 Pen formulations are particularly preferable for older patients with impaired vision or dexterity.29 In addition, when patients must mix insulins, errors are more likely to occur. The use of premixed insulin vials has been shown to increase dosing accuracy when used by the elderly.30
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