Adapted from Diabetes in Older Adults: A Consensus Report, Journal of the American Geriatric Society
Insulin therapy can be used to achieve glycemic goals in selected older adults with type 2 diabetes with similar efficacy and hypoglycemia risk as in younger patients.
However, given the heterogeneity of the older adult population, the risk of hypoglycemia must be carefully considered before using an insulin regimen to achieve an aggressive target for hyperglycemia control. A mean A1C of 7% was achieved and maintained for 12 months with either an insulin pump regimen or multiple daily insulin injections in otherwise healthy and functional older adults (mean age 66 years), with low rates of hypoglycemia. The addition of long-acting insulin was similarly effective in achieving A1C goals for older patients with type 2 diabetes (mean age 69 years) in a series of trials with no greater rates of hypoglycemia than in younger patients (mean age 53 years). However, there are few data on such regimens in people aged >75 years or in older adults with multiple comorbidities and/or limited functional status who were excluded from these trials. Problems with vision or manual dexterity may be barriers to insulin therapy for some older adults. Pen devices improve ease of use but are more costly than the use of vials and syringes.
Hypoglycemia risk (especially nocturnal) is somewhat lower with analog compared with human insulins, but the former are more expensive. Insulin induced weight gain is a concern for some patients, and the need for more blood glucose monitoring may increase treatment burden.
Vulnerability to Hypoglycemia
Age appears to affect counter-regulatory responses to hypoglycemia in nondiabetic individuals. During hypoglycemic clamp studies, symptoms begin at higher glucose levels and have greater intensity in younger men (aged 22–26 years), while measures of psychomotor coordination deteriorate earlier and to a greater degree in the older subjects (aged 60–70 years), erasing the usual 10–20 mg/dL plasma glucose difference between subjective awareness of hypoglycemia and onset of cognitive dysfunction. Studies in older individuals with diabetes are limited.
One small study compared responses to hypoglycemic clamps in older (mean age 70 years) versus middle-aged (mean age 51 years) people with type 2 diabetes. Hormonal counter-regulatory responses to hypoglycemia did not differ between age groups, but middle-aged participants had a significant increase in autonomic and neuroglycopenic symptoms at the end of the hypoglycemic period, while older participants did not. Half of the middle-aged participants, but only 1 out of 13 older participants, correctly reported that their blood glucose was low during hypoglycemia. The prevalence of any hypoglycemia (measured blood glucose below 70 mg/dL) or severe hypoglycemia (requiring third-party assistance) in older populations is not known.
In the ACCORD trial, older participants in both glycemic intervention arms had ~50% higher rates of severe hypoglycemia (hypoglycemia requiring third-party assistance) than participants under age 65 years. In a population analysis of Medicaid enrollees treated with insulin or sulfonylureas, the incidence of serious hypoglycemia (defined as that leading to emergency department visit, hospitalization, or death) was approximately 2 per 100 person-years, but clearly studies based on administrative databases miss less catastrophic hypoglycemia.
The risk factors for hypoglycemia in diabetes in general (use of insulin or insulin secretagogues, duration of diabetes, antecedent hypoglycemia, erratic meals, exercise, renal insufficiency) presumably apply to older patients as well. In the Medicaid study cited above, independent risk factors included hospital discharge within the prior 30 days, advanced age, black race, and use of five or more concomitant medications.
Assessment of risk factors for hypoglycemia is an important part of the clinical care of older adults with hypoglycemia.
Education of both patient and caregiver on the prevention, detection, and treatment of hypoglycemia is paramount.