ACTID Results Emphasize Diet Alone Over Diet and Exercise

Neil Canavan

June 26, 2011

June 26, 2011 (San Diego, California) — The good news provided by the results of the British ACTID (Early Activity in Type 2 Diabetes) trial, announced here at the American Diabetes Association (ADA) 71st Scientific Sessions, was that intensive dietary intervention and dietary intervention combined with an increase in moderate activity were both greatly superior to usual care in a real-world comparison of diabetic patients in the first 6 months after being diagnosed.

Full results of the ACTID study have been published simultaneously in the Lancet.

Dr. Robert Andrews

Despite expectations, the addition of exercise to diet provided no additional benefit over diet alone, said lead ACTID investigator, Robert C. Andrews, MB, ChB, PhD, and who is senior lecturer at the University of Bristol, United Kingdom.

Our study aimed to add to evidence from previous studies that "people who exercise or stick to a diet get improvement in their diabetes control. Ours differs in that no one has gone out and done a real-world trial in which they've taken all comers." Nor has diet, with or without exercise, been previously compared in this population, Dr. Andrews noted.

In the ACTID trial, 593 patients in the early stages of type 2 diabetes were randomized to 1 of 3 groups: usual care — which consisted of a standard, brief education session that offered dietary and exercise advice, with follow-ups at 6 and 12 months; diet alone — which involved far more detailed dietary information, with more time spent with the patient per visit, and follow-ups at 3, 6, 9, and 12 months; and diet plus exercise — which involved detailed dietary information and an additional focus on increasing the amount activity, in this case walking, to at least 30 minutes a day, 5 days a week. Patients in the diet plus exercise group were given motivational literature, a pedometer, and a diary to record daily activity.

The primary end point of the ACTID study was improvement in glycosylated hemoglobin (HbA1C). Study results were reported for 6-month and 1-year time points.

"If you were in the usual care arm, during the first 6 months your diabetes control worsened, whereas in the diet alone and the diet and exercise arms, it got slightly better," said Dr. Andrews. After 6 months, and according to study protocol, patients were treated to an HbA1c target of 7.5%; again, the usual care group did significantly worse than the other 2 groups (P = .0001). Surprisingly, there was no difference between the diet alone and the diet plus exercise groups (P = .6).

This initial finding was replicated for the study's secondary end points of weight loss, insulin resistance, and the amount of medication used to control blood sugar at 1 year. Again, the usual care group fared consistently, strikingly worse than the other 2 groups; the diet alone and the diet plus exercise groups had beneficial outcomes virtually identical to each other.

"Obviously, the question is: Why did we not get an increase [in benefit] with additional activity?," Dr. Andrews said.

One possibility is that the activity chosen — walking (a pragmatic choice) — was suboptimal. "A study by Church in JAMA [2010;304:2253-2262] suggested that if you do resistance or aerobic exercise alone, you don't get significant improvement. You have to do a combination."

Alternatively, activity itself might be the wrong focal point. After "comparing activity and waistline circumference at baseline," Dr. Andrews explained, "we found that waist circumference was not so much related to the amount of moderate activity you had been doing, but to the amount of time you spend doing absolutely nothing — what's called 'sedentary time'." This suggests that it's better to concentrate on changing your patient's sedentary time rather than insisting on more moderate activity, he said.

Dr. Andrews offered one other possible explanation, which he calls "trading." He explained that "after interviewing patients, we found that those in the diet and exercise arm admitted that if they knew they were going to the gym, they could have something extra, some treat just before, and then work out just a bit harder."

Regardless of the reason, Dr. Andrews suggested that the true utility of the results is to stress that in these times of budgetary constraint, diet alone is a legitimate first-line approach to diabetes control. He added that the ACTID program itself was cost effective, and estimated that the savings realized by avoiding the use of diabetes medications covered the cost of the interventions required by those receiving usual care over 1 year.

ADA Attendees Puzzled But Impressed

Dr. Sue Kirkman

Commenting at a press briefing during which the ACTID results were highlighted, Sue Kirkman, MD, senior vice president of medical affairs and community information for the ADA, suggested that listeners focus on the big picture.

"I did find it a little surprising that there was no additional benefit of exercise. Perhaps people didn't adhere as well to the diet, or perhaps the diet approach is so powerful at the beginning that exercise doesn't add that much," Dr. Kirkland noted. "But the overall results — that both lifestyle arms had such obvious benefit — were no surprise. If you compare the evidence from prediabetes studies, for example, you see that changes in lifestyle, say with modest weight loss, or moderate exercise provide these benefits as well."

Responding to no small amount of consternation during the press briefing, Dr. Andrews was adamant that the ACTID results and their implications not be misunderstood.

"We're not saying that exercise isn't useful, it simply didn't improve the parameters that we measured. There is clear evidence out there that individuals who exercise have reduced rates of cancer, reduced mortality, and other benefits from exercising, such as enhanced sense of well being." Include exercise if you can, but dietary change should be the focus of your lifestyle intervention, Dr. Andrews emphasized.

Dr. Andrews reports serving as a board member for GSK; being on an advisory board for GSK; and being on the speaker's bureau for GSK, Eli Lilly, Novartis, and Sanofi-Aventis.

Lancet. Published online June 25, 2011. Abstract

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