Elderly patients with new-onset diabetes form a unique group

Marlene Busko

July 31, 2013

July 31, 2013

Hadera, Israel - Among elderly patients with new-onset diabetes, poor glycemic control—an HbA1c of >7.5%—was linked with increased mortality risk, in a new study [1]. But the researchers did not find a U-shaped risk pattern, unlike that reported for elderly patients with long-standing diabetes.

In the current study, patients with the highest levels of HbA1c also were least likely to undergo a coronary revascularization procedure.

This is the first published study that examined how HbA1c levels, mortality, and coronary revascularization were related in elderly patients with new-onset diabetes, write Dr Orit Twito (Hillel Yaffe Medical Center, Hadera, Israel) and coauthors.

"We think that the findings were very interesting, especially because they are totally different from the results in elderly with long-standing diabetes," she said in an email. "We have to treat separately and differentially patients [with] different ages, different gender[s], and different . . . disease [duration]," she stressed.

"I believe that guidelines should mention these results, but more research is needed in this population," since this was an epidemiologic study, she added.

The study was published online July 22, 2013 in Diabetes Care.

Unique population

The researchers conducted a retrospective observational study of data from a cohort of 2994 individuals (48% males) living in the Sharon-Shomron District, Israel, who were insured by a large provider.

The study subjects were 65 years or older when they were newly diagnosed with diabetes in 2003 or 2004. The patients were assumed to have type 2 diabetes, since type 1 diabetes is very rare at this age, and only 0.1% to 3% of the patients were receiving insulin therapy, Twito noted.

The patients were followed for seven years or until they reached a study outcome: coronary revascularization—PCI or CABG—or mortality.

At baseline, patients had a mean age of 75.6 years. They were stratified into four groups, based on their average HbA1c levels during follow-up: less than 6.5% (n=1580), 6.5% to 6.99% (n=611), 7% to 7.49% (n=367), and 7.5% or greater (n=436).

HbA 1c
and mortality

During a mean follow-up of 5.54 years, 1173 participants (39.17%) died. All-cause mortality rates were 41%, 32%, 36%, and 46%, in the four groups, respectively.

Compared with participants in the group at lowest risk of dying (those with an average HbA1c level of 6.5% to 6.99%), patients in the group with the highest HbA1c levels (>7.5%) had a significant increased mortality risk.

Adjusted hazard ratios for all-cause mortality*


HbA 1c (%)
HR (95%CI)
<6.5
1.03 (0.9-1.2)
6.5 - 6.99
1.00 (reference group)
7 - 7.49
1.2 (0.99-1.5)
> 7.5
1.4 (1.1-1.6)

*Adjusted for traditional cardiovascular risk factors, hypoglycemia medications, and statins

These findings differ from a previous large, retrospective cohort study of patients older than 50 who had long-standing diabetes and intensive hypoglycemic treatment, where researchers reported finding a U-shaped risk pattern, and an HbA1c level of about 7.5% was associated with the lowest all-cause mortality [2].

"The difference in mortality patterns between our finding and the aforementioned study underscores the need to differentially treat elderly patients with new-onset [diabetes] and elderly patients with long-standing disease," the researchers write.

HbA 1c
and coronary revascularization

During follow-up, 285 participants (9.51%) underwent PCI or CABG. The rate of coronary revascularization was highest in the patients with an average HbA1c level of 6.5% to 6.99% and lowest in the patients with an HbA1c level of >7.5%.

This inverse relationship may be the result of a protective effect of revascularization against mortality, or the patients with the highest levels of HbA1c may have received suboptimal medical treatment for various reasons, the investigators speculate.

"Further research is needed to determine the recommended glycemic-control target in this unique population," the authors conclude.

The authors have reported no relevant financial relationships.

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