We found that 12.2% of people with type 2 diabetes in our population had a mean 3-year weight-change trajectory that included a clinically significant (9.8% at 18 months) (2
) mean weight loss. Despite weight regain during the 3-year period, those who initially lost weight had improved glycemic and blood pressure control in year 4 compared with that in groups with stable or weight-gain trajectories. These findings suggest that, even in the face of weight regain (15
), losing weight can have long-lasting benefits in type 2 diabetes. The therapeutic advantage achieved through weight loss is exceedingly important given the close connection between glycemic and blood pressure control (especially in the first years postdiagnosis) and cardiovascular outcomes (16
Although helping patients achieve weight loss can be overwhelming (18
), physicians can feel encouraged by the weight trajectories we observed in free-living people with type 2 diabetes during the 3 years after initial diagnosis. Some people achieved weight loss despite the fact that the study site, similar to many communities (18
), directs fewer resources to weight loss than to monitoring and medications. Practitioners frustrated by the frequency of weight regain (15
) may be reinvigorated by our finding that weight regain in diabetes may not imply lack of therapeutic benefits of weight loss.
The weight-loss group, on average, began regaining at about 18 months. This suggests that the first months postdiagnosis may provide a window to capitalize on patient and clinician motivation by actively applying weight-loss interventions. However, additional support for maintaining weight loss will be important.
Recent findings from the Look AHEAD weight loss in diabetes study revealed that the intensive lifestyle intervention group lost, on average, 8.6% of their initial weight at 1 year, compared with 0.7% in the education control group (3
). The magnitude of weight change noted in our community weight-losing cohort was similar. At year 4, the absolute A1C and blood pressure differences between those who lost or gained weight were small but similar to differences observed between intervention and control subjects in Look AHEAD (3
). The A1C effects seen here are clinically significant: prior studies have concluded that every percentage point reduction in mean A1C correlates with a 37% reduction in risk of microvascular complications and a 21% reduction in risk of any diabetes-related end point and diabetes-related deaths. No threshold has been observed for these risks (19
). Risk of death from ischemic heart disease and stroke also increases progressively and linearly starting from blood pressure levels as low as 115/75 mmHg (20
Last, our models controlling for medication use in year 4 may have provided conservative estimates of effects of weight trajectories on A1C control, in that diabetes medication use likely also affects weight trajectories (21
). The weight-loss group had little change in metformin use (often associated with weight loss) (21
). Thus, medication use patterns cannot explain the improved trajectory and A1C patterns in the weight-loss group.
Our study has several limitations. The study was conducted at one HMO in two states, so findings may not be generalizable to other settings. We studied only survivors, so we do not know weight-change patterns for everyone or how they related to outcomes. However, our study was strengthened by access to many measures taken in a large group of community-based diabetes patients, including diagnostic data that might suggest unintentional weight change. Our data were collected during clinical care; thus, weight and other measurements may not have been as precise or complete as they would be during a clinical trial. For example, we did not have a true baseline A1C on all patients and, instead, used year 1 findings. However, this was a conservative approach, and findings were largely unchanged when analyses were restricted to those with a baseline measure.
We did not evaluate possible mechanisms that might explain the improved A1C and blood pressure control observed in the weight-loss group. The lasting benefit, in spite of weight regain, may derive from increased insulin sensitivity remaining from weight loss (22
); mechanisms related to “metabolic memory” (23
); lifestyle changes accompanying weight loss, such as improved diet or increased activity; or other unmeasured factors that differed among the weight-trajectory groups. We did not evaluate which behaviors led to weight change. These areas should be the focus of future research. Interestingly, the strength of the trajectory method is highlighted by the finding that baseline BMI alone did not significantly predict above-goal A1C in year 4.
We conclude that, in this analysis, a weight-loss trajectory predicted improved glycemic and blood pressure control when compared with stable-weight or weight-gain trajectories. In light of previously reported positive effects of weight loss on therapeutic outcomes in people with diabetes (3
) and our added findings of the natural history of weight loss and outcomes in diabetes in the community, more focus should be placed on helping clinicians implement programs to manage weight trajectories in new diabetic patients.