Chicago, IL - An aggressive approach to glucose control for diabetic patients undergoing elective cardiac surgery does not improve outcomes or reduce length of stay—and may even be harmful, the Neurological Outcomes in Diabetics Undergoing Cardiovascular Surgery (NODS) trial suggests [1].
Dr Jorge Calles (Case Western Reserve University, Cleveland, OH) presented interim results on blood glucose and complications from this prospective, randomized, single-center trial earlier this week at the American Diabetes Association (ADA) 2013 Scientific Sessions.
"Our data support refining the current ADA guideline of glycemia management in noncritical hospitalized patients postcardiovascular surgery," Calles said.
"Rather than just [saying] glucose should be < 180 mg/dL, I would recommend to diabetologists and internists that we really need to keep our patients in a safe range of glycemia of > 140 [and < 180 mg/dL], due to safety reasons and lack of improved outcomes."
As Calles explained, current ADA guidelines provide recommendations on drug choice and target blood glucose for patients in intensive care, but there is no clear evidence addressing whether a similar approach is warranted in noncritically ill patients discharged to hospital wards. If treated with insulin, Calles said, premeal blood glucose targets are generally recommended to be < 140 mg/dL (7.8 mmol/L) with random blood glucose < 180 mg/dL (10.0 mmol/L).
"More stringent targets may be appropriate in stable patients with previous tight glycemic control, while less stringent targets may be appropriate in those with severe comorbidities," he said, noting that that recommendation is given a level of evidence "E" (expert consensus or clinical experience, in the absence of studies and randomized trials).
A small, focused trial
Calles and colleagues hypothesized that outcomes would be better if diabetic patients undergoing and recovering from CV surgery were treated more intensively: to a fasting blood glucose of < 120 mg/dL and a daytime level of < 150 mg/dL, rather than using the more commonly used levels of < 200 mg/dL or < 180 mg/dL.
In NODS, 121 diabetic patients were randomized within 48 hours prior to their CABG or valve procedure to either an intensive or conservative strategy.
In the intensive-strategy group, IV insulin was started "right away," Calles said, and maintained during surgery and in the ICU, with preop, surgery, and postsurgery ICU targets of finger-stick glucose at 100 to 140 mg/dL. Once transferred to the ward, intensive-group patients were maintained at fasting targets of < 120 mg/dL and daytime targets of < 150 mg/dL.
In the conservative group, IV insulin was started during surgery and monitored according the anesthesiologist. Once on the ward, monitoring was at the discretion of the cardiovascular-surgery attendee, with the aim of keeping glucose levels
< 180-200 mg/dL.
Glucose outcomes and complications
As Calles showed here, average blood glucose levels postsurgery were significantly lower in the intensive group as compared with the conservative group for the first five days postsurgery. "So we achieved our goal of a nice separation [of blood glucose levels between groups], as well as our goal of daytime and nighttime targets.
"But what happened with real outcomes?" Calles asked. "Much to my dismay, the rate of hypoglycemia was higher in the patients I treated intensively than in the patients that the CV surgeons treated."
Length of stay, readmissions, and infection rates were no different between groups, but the stroke rate was numerically higher in the intensive group.
"And this is what really put a halt on us: there were three strokes in the intensive group and one in the standard group. This threefold higher risk of stroke is very similar to a study reported by the Mayo Clinic five years ago.
"We didn"t find any clinical advantage of going for a very intensive regimen vs a standard regimen in CV surgery patients in the ward," he concluded.
NODS investigators will also be reporting, at a later date, any neurological changes, postsurgery, seen in their trial.
New targets, for a precarious group?
To heartwire, Calles said that how diabetic patients undergoing CV surgery are managed differs from hospital to hospital.
"Broadly speaking, there are two groups of people, the internal-medicine group, that are not so aggressive and who are leaving the patients to the sliding scales only, with their glucose bouncing all over the place. And then there are those who are more conscientious about making sure the diabetes is controlled in the hospital. That includes the CV surgeons, the cardiologists, some endocrinologists. So if you happen to be in one of those areas in the hospital where the CV surgery is dominant or the cardiologist is taking care of you, then you might have a more intensive approach to glycemia."
Calles acknowledged that his study was small, but he thinks it is "persuasive enough" to influence guideline-writing committees. To answer the broader question of whether intensive treatment would offer some benefit in all diabetic patients undergoing general surgery would require a trial of thousands and thousands of patients.
"Sometimes small trials, that have a very fine focus, like this one, and are well-executed and the data are clean—that should be enough to persuade clinicians to make a change, at least [when treating] the type of patients we studied [diabetic patients undergoing elective cardiovascular surgery]. This can"t be applied to any other patients besides these," he stressed.
And cardiovascular-surgery patients are, in many ways, special, he pointed out. "The diabetic patient who requires bypass is a patient who has very advanced vascular disease, is very fragile, is in a very precarious situation. And then you have the surgeons munch-munching on the heart: it"s a very aggressive treatment."
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