Weight gain does not necessarily follow the institution of insulin therapy in type 2 diabetes patients already taking oral hypoglycemics, results of a 7-year longitudinal study suggest.
Study investigators concluded that weight gain following the addition of insulin therapy is mostly the result of a correction of the glycemia that often causes weight loss, and brings most patients closer to their normal physiologically controlled weight.
“Thus, concern over an increase in body weight should not deter patients and physicians from adding insulin and appropriate oral medications in order to achieve therapeutic goals,” Dr. Ohad Cohen of Tel Aviv University, and his coauthors wrote in Diabetes Research and Clinical Practice.
The study included 366 adults (mean age 67 years) with type 2 diabetes. Most (310) were on only oral hypoglycemic medications at baseline; the remaining 56 were also taking insulin (Diabetes Res. Clin. Pract. 2008;79:128–32). Compared with those taking oral medications, patients also on insulin had an earlier age of diabetes onset (51 vs. 55 years) and longer duration of diabetes (13 vs. 6 years).
Mean baseline weight was 79 kg; the mean self-reported weight before diagnosis was 83 kg.
Patients followed a stepwise diabetes therapy, beginning with modified nutritional therapy followed by oral medications. Insulin was added if oral therapy failed to reach the glycemic goal of a hemoglobin A1c level of less than 8%.
Weight among those taking only the oral medications stayed constant throughout the 7-year follow-up period, with no changes occurring after the transition from nutritional therapy to oral medication, and no significant difference from baseline to the end of follow-up.
In contrast, patients who added insulin to their treatment regimen experienced significant weight gain, gaining a mean of 2 kg in the period between the change and the end of the study.
However, the investigators noted, insulin was added at a time when the patients' blood glucose levels increased significantly to a mean of 9.4%; this increase was accompanied by a nonsignificant weight decrease. The mean weight increase of 2 kg did not cause patients to exceed their self-reported prediagnosis weight, or to significantly exceed their weight when treated by diet alone.
A large weight increase of more than 10 kg occurred in 22 subjects. Multivariate analysis identified younger age, higher HbA1c levels, lower initial body mass index, and the absence of atherosclerotic heart disease as risk factors for high weight gain.
“The data uniquely present clear evidence that the increase in weight of diabetic patients, who in real life use insulin, is relative to their previous uncontrolled state preceding insulin usage and does not surpass the weight during previous stages of the disease,” the authors said.