Both patient age and the duration of type 2 diabetes independently determine the clinical course of the disease among adults aged 60 to 80-plus years, according to a report published online Dec. 9 in JAMA Internal Medicine.
The cardiovascular complications of diabetes are considered the most common as well as the most serious complications in patients of all ages, and preventing them by concentrating on glycemic control has been the mainstay of diabetes management. But this large cohort study showed that among older patients and those with longer disease duration, hypoglycemia rates approached those of coronary artery disease, said Dr. Elbert S. Huang of the University of Chicago and his associates in the Diabetes and Aging Study.
This means that the core focus on glycemic control is inappropriate for a substantial number of older diabetes patients. "To the extent that hypoglycemia is an adverse effect of treatment, its emergence as a dominant ‘complication’ raises serious concerns about the acceptable limits of iatrogenesis," they noted.
Dr. Huang and his colleagues examined the clinical course of type 2 diabetes in older adults because "most of our current understanding" is based on studies from the 1990s," and diabetes care has evolved since that time.
They analyzed data from the Kaiser Permanente Northern California Diabetes Registry concerning 72,310 diabetes patients aged 60 years and older at baseline in 2004. These study participants were followed for up to 7 years (mean follow-up, 5.4 years) for acute hyperglycemic events requiring hospitalization; acute hypoglycemic events requiring emergency department visits or hospitalization; microvascular complications such as severe eye disease, incident end-stage renal disease, peripheral vascular disease, and amputation; nonfatal cardiovascular complications such as myocardial infarction, coronary artery bypass graft surgery, angioplasty, ischemic or hemorrhagic stroke, carotid endarterectomy, and congestive heart failure; and fatal complications of any kind.
The mean patient age was 71 years, and about 15% of the study population was aged 80 years and older. The cohort was ethnically diverse and had equal access to health care, and most patients were receiving statins and angiotensin-converting enzyme (ACE) inhibitors appropriately.
Both patient age and duration of type 2 diabetes had a significant, independent effect on which complications were likely to arise. "Most notably, the risk of hypoglycemia rose markedly" with increasing age and duration of disease, so that it outpaced both coronary and cerebrovascular events as the most common serious complication in this subset of the population, the investigators reported (JAMA Intern. Med. 2013 Dec. 9 [doi: 10.1001/jamainternmed.2013.12956]).
Hypoglycemia was even fairly frequent among younger patients: It was the fourth most common complication among patients in their 60s and the third most common among patients in their 70s.
The rate of hypoglycemic events ranged from a low of 3.0 per 1,000 person-years among the youngest patients with the shortest duration of disease to a high of 19.6 per 1,000 person-years among the oldest patients with the longest duration of disease. (The corresponding rates of coronary artery disease events were 8.5 and 24.1 per 1,000 person-years.) This suggests that intensive glycemic control may not be a helpful treatment goal and may even be harmful to the latter group.
In addition, among the oldest patients who had a long duration of diabetes (more than 10 years), the rate of acute hyperglycemic events was only 2.35 per 1,000 person-years. This also suggests that intensive glycemic control to guard against hyperglycemic events may not be helpful in such patients.
"Our observations ... provide additional support for the reorientation of care of older patients with diabetes away from intensive glycemic control as the core focus of management. The distinctive clinical course of different patient strata supports recommendations to individualize glycemic targets among older people," Dr. Huang and his associates said.
The Diabetes and Aging Study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the University of Chicago. No financial conflicts of interest were reported.