Activity Dips After Insulin Therapy Among Nonobese With Diabetes

Norra MacReady

July 19, 2017

Weight gain associated with starting insulin therapy for type 2 diabetes appears to be related more to an increase in sedentary behavior than a decrease in physical activity, according to new findings.

And the weight gain occurred almost exclusively in people with a body mass index (BMI) less than 30 kg/m2, compared with people whose BMI was 30 kg/m2 or higher, reserchers write in a letter published online July 10 in Diabetes Care.

"This suggests that increased sedentary behavior, especially in nonobese type 2 diabetes patients, may contribute to body weight gain after initiation of insulin therapy," they note, adding that "sedentary behavior assessment and intervention may be needed in type 2 diabetes management."

Lead author Yvonne Hartman, MD, of Radboud University Medical Center, Nijmegen, the Netherlands, and colleagues studied 40 patients randomly chosen from hospital clinics and primary-care practices. Body weight, waist-to-hip circumference, fasting glucose, and HbA1c were measured before patients began taking insulin and 6 and 12 months after.

Starting at baseline, free-living daytime physical activity was measured by having patients wear armband monitors that tracked their steps and energy expenditures. The participants also kept daily food diaries.

At the 12-month follow-up visit, mean body weight of the cohort had increased by 2.9 kg (6.4 lb) (standard deviation ± 4.5 kg (9.9 lb); P < .05), although fasting glucose and HbA1c both significantly decreased.

There was also a decrease in the number of daily steps and sit-to-stand transitions recorded for the group overall, from a mean of 7854 ± 3936 to 6060 ± 3022 steps and from 20 ± 5 to 18 ± 6 sit-to-stands, respectively (P < .05, both comparisons).

In general, people with BMI less than 30 kg/m2 spent less time sitting and more time engaged in low-intensity physical activity, defined as 2.1 to 3.0 metabolic equivalents (METs), compared with patients with a higher BMI.

However, in those with a BMI less than 30 kg/m2, their BMI and waist circumference increased after they began insulin therapy, a finding not seen in patients with a starting BMI 30 kg/mor higher.

"Similarly," the authors write, "patients with BMI < 30 kg/m2 but not those with BMI ≥ 30 kg/m2 demonstrated an increase in sitting time and a decrease in energy expenditure and steps/day," associated with the changes in weight and waist circumference.

Logistic regression analysis confirmed this relationship, showing a significant correlation over 12 months between insulin therapy, change in sitting time, and increase in weight (r = .446; P = .033) and waist circumference (r = .446; P = .037) in this group of patients.

The authors also point out that moderate to vigorous activity, defined as more than 3.0 METs, did not change significantly in either group, and energy intake actually declined from a mean 1721 ± 839 calories/day to 1460 ± 367 calories/day (P = .074).

These results may be because of a "ceiling effect in sedentary behavior in patients with BMI ≥ 30 kg/m2," they write. "Indeed, the average sitting time of 12.5 hours [for this group] makes it practically difficult to further increase sedentary behavior."

The authors have reported no relevant financial relationships.

Diabetes Care. Published online July 10, 2017. Article

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