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by Ashley Bizzell, PharmD Candidate, & Lisa C Hutchison, PharmD, MPH 

University of Arkansas for Medical Sciences

Older adults with diabetes find it more difficult to control their blood glucose and reach target hemoglobin A1C values.  One reason they have more difficulty is the difference in pharmacokinetics that medications have in older adults, specifically changes in absorption, distribution, metabolism, and excretion. Antidiabetic medications in particular can cause serious consequences in older adults if not prescribed and used appropriately; following literature recommendations and guidelines can be helpful to ensure both efficacy and safety of these drugs in elderly patients.

One major concern for older adults is their risk for hypoglycemia with antidiabetic medications. This can lead to serious consequences including increased risk for falls, fractures, and central nervous system decline.  For these reasons, target hemoglobin A1C (Hgb A1C) goals are less stringent in older adults where clinicians should aim for a Hgb A1c of 7.5 to 8% as compared to less than 7% for younger adults.1

After the target Hgb A1C has been determined, therapy must be selected.  If lifestyle changes are inadequate to reach target Hgb A1C, diabetes can be managed with different classes of medications.  However, one must recognize which medications to avoid in older adults, especially in those with renal insufficiency, cardiovascular disease, or polypharmacy. Sulfonylureas such as glipizide and glyburide should be used with caution in older adults as they pose an increased risk for hypoglycemia. The AGS Beers Criteria specifically recommends against the use of glyburide in older adults as the risk for hypoglycemia is too high.2 Another class of concern are the insulins which can be very effective for controlling blood glucose, but can also be problematic  in the elderly patient. First, insulins are currently only available for subcutaneous injectable administration, which can be difficult for elderly patients with physical or cognitive impairment.  Long-acting insulins such as insulin glargine or insulin detemir are preferred forms of insulin for older adults as these insulins have a decreased risk for hypoglycemia and allow for easier regimens with fixed doses only once or twice a day in contrast to short-acting insulins such as insulin lispro or insulin aspart which can have more complex regimens.3  Although insulin can be used safely to manage blood glucose in older adults, the AGS Beers Criteria recommends against the use of insulin sliding scales for chronic management as this dosing regimen carries an increased risk of hypoglycemia.2

Metformin remains a first line agent for diabetes that is relatively safe and effective.  This is a preferred option in older adults unless renal insufficiency is present.  The most common adverse effects of metformin are diarrhea, nausea, and vomiting.  Recent studies alert clinicians to the risk of vitamin B12 and folic acid deficiency, recommending testing before signs or symptoms of deficiency are evident.4 These micronutrients should be monitored annually along with hemoglobin and renal function.

Glucagon-like peptide-1 (GLP-1) agonists, including exenatide and liraglutide, have also been used safely and effectively in older adults, however there are no studies specifically in the older adult population. Dipeptidyl peptidase-4 (DPP-4) inhibitors including sitagliptin and saxagliptin are also considered relatively safe in older adults. Because their actions are glucose dependent, they have low risk for hypoglycemia with similar efficacy to other classes.3   However, GLP-1agonists and DPP-4 inhibitors require dosing adjustments in patients with renal insufficiency.

When treating older adults for diabetes, one must use an individualistic approach with added caution in this population due to multiple co-morbidities. Guides such as the AGS Beers Criteria can help guide decisions for the busy clinician.

 

 

References:

  1. “AGS Beer’s Criteria for Potential Inappropriate Medication Use in Older Adults.” The American Geriatrics Society, 2015. Accessed 26 July 2017.
  1. “American Diabetes Association Standards of Medical Care in Diabetes—2017.” The Journal of Clinical and Applied Research and Education, Diabetes Guidelines, vol. 40, no. 1, Jan. 2017, p. S50. Accessed 26 July 2017.
  1. Kim, Kyung S., Soo K. Kim, Kyung M. Sung, Yong W. Cho, and Seok W. Park. “Management of Type 2 Diabetes Mellitus in Older Adults.” Diabetes and Metabolism Journal, 2012, pp. 336-44. Accessed 26 July 2017.
  1. Kancherla, V, Elliott, JL, Patel BB, et al. “Long-term Metformin Therapy and Monitoring for Vitamin B12 Deficiency Among Older Veterans.”  J Am Geriatr Soc, 2017, 65:1061-6.