No Butts About It, Sitting Less Is Beneficial in Diabetes

Kristin Jenkins

December 01, 2016

In patients with type 2 diabetes, a "Sit-Less" intervention that breaks up sedentary behavior with standing and light-intensity walking appears to be "more potent" than structured exercise at achieving glycemic control and improving insulin sensitivity, a new study indicates.

Replacing sitting time with standing and walking around the house could provide a valuable exercise alternative for patients with type 2 diabetes, particularly when muscle weakness and peripheral neuropathy make it difficult to exercise, according to the researchers.

"In this study, we observed that the Sit-Less regimen improved insulin sensitivity, mean 24-hour glucose levels, 24-hour glucose excursions, duration of hyperglycemia [blood glucose ≥10 mmol/L], and fasting triacylglycerol levels," say Bernard MFM. Duvivier, MD, of the CARIM School for Cardiovascular Diseases, Maastricht University Medical Center, the Netherlands, and colleagues in a report published online November 30 in Diabetologia.

"These data suggest that more stable glucose levels can be achieved with light-intensity activity rather than with exercise."

While structured exercise is a well-recognized part of diabetes treatment and prevention, the dropout rate in healthy individuals is about 90%, the researchers point out. "Sustained compliance with exercise programs, especially by individuals with type 2 diabetes, is at best mediocre."

The duration of activity during the day — rather than the intensity — may be more important for glycemic control, Dr Duvivier and colleagues hypothesized.

"The outcome of the present study fits the emerging picture that breaking up sedentary behavior by light-intensity activities may help to improve glucose homeostasis in groups, ranging from young lean normoglycemic individuals to overweight/obese normoglycemic and dysglycemic participants."

Sitting Has Negative Effects on Insulin Sensitivity

In their randomized crossover study, which was conducted between March and May 2015, they enrolled 13 men and six women with type 2 diabetes who were not using insulin.

Mean age of the participants was 63 years, and the mean duration of disease was 6 years. Mean body mass index (BMI) was 30.5 kg/m2, which is defined as obese.

Fourteen participants were taking oral glucose-lowering medications and 13 were using lipid-lowering drugs, primarily statins.

During screening, the participants had a mean fasting plasma glucose of 7.88 mmol/L and a mean HbA1c of 6.7%.

The participants followed three activity regimens that lasted 4 days each.

In the "Sitting" regimen, participants were restricted to 1 hour a day of walking and 1 hour a day of standing. The rest of the 14-hour day was spent sitting.

The "Exercise" regimen replaced 1 hour of sitting time with supervised cycling on an exercise bike at the research center. Participants cycled in 20-minute intervals with 5 minutes of rest in between.

In the "Sit-Less" regimen, participants were asked to interrupt sitting every 30 minutes and replace it with small bouts of walking (for a total of 2 hours per day) and standing (for a total of 3 hours each day).

The order in which participants underwent the different regimens was randomized and for 10 days between each regimen, they were told to go about their normal daily routine.

Results showed that the incremental area under the curve (iAUC) for 24-hour glucose was significantly lower during the "Sit-Less" intervention than when the same participants sat for 14 hours a day as part of a sitting regimen (1263 min × mmol/L vs 1974 min × mmol/L; P = .002).

Although iAUC was similar when study participants engaged in 1 hour of moderate cycling each day as part of the exercise regimen (1383 min × mmol/L; P = .499), the Sit-Less intervention was much more effective at reducing insulin resistance (HOMA2-IR) when compared with just sitting (P = .001) or cycling (P = .015).

Previously, the researchers demonstrated similar results in healthy individuals who were sedentary. Replacing sitting time with standing and light-intensity walking in free-living conditions was also more efficient than a single daily session of moderate exercise at improving insulin sensitivity, even in the absence of diabetes.

"These data suggest that sitting has negative effects on insulin sensitivity independent of energy expenditure," they point out. One bout of exercise probably cannot fully compensate for the negative effects of sitting for the rest of the day."

Strategies to reduce sitting time are also generally considered less demanding than structured exercise, so the chances of sustained compliance are greater, Dr Duvivier and colleagues note.

What's needed now are long-term studies to determine just how much low-intensity activity "is feasible in daily life," they say.

Population-based studies suggest that adults spend more than half of their day at sedentary activities such as watching TV and sitting at a computer. In addition, observational studies point to "associations between the time spent sitting and markers of metabolic disturbance," the researchers point out.

The study was supported by Maastricht University Medical Center and the Dutch Heart Foundation and partially funded by a Kootstra Talent Fellowship from the Center for Research Innovation, Support and Policy of Maastricht University Medical Center to Dr Duvivier. The study received additional funding from Novo Nordisk BV and the Netherlands Cardiovascular Research Initiative: an initiative with support of the Dutch Heart Foundation. The consumables for continuous glucose monitoring and glucose measurements were supplied by Medtronic and Roche. Novo Nordisk BV was involved in study design and editorial assistance. The authors report no relevant financial relationships.

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Diabetologia. Published online November 30, 2016. Abstract

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