Risk of diabetes diagnosis higher in those who lost weight after age 25, but study finds result statistically insignificant.
In a current study with 21,544 patients, researchers found that adults with obesity who lost weight between young adulthood and midlife had a significantly lower risk of developing incident diabetes over 10 years, as did adults without obesity who developed obesity, compared with adults with stable obesity.
The study was done to determine the association between self-reported weight change from young adulthood to midlife and incident diabetes. They categorized individuals into four weight-change groups: those who remained without obesity (stable non obese), those who moved from an obese BMI to a non-obese BMI (losing), those who moved from a non-obese BMI to an obese BMI (gaining), and those who remained with obesity (stable obesity). Diabetes status was determined by self-report of a prior diagnosis, and age at diagnosis was used to establish time of diabetes onset. Hazard ratios (HRs) relating weight change to incident diabetes over 10 years of follow-up were calculated using Cox models adjusting for covariates.
Those who had obesity and lost weight exhibited a significantly lower risk of diabetes compared with those with stable obesity. Also observed was a lower risk among those who had stable non obesity and those in the gaining category. Further, there was evidence of an increased incidence of diabetes among individuals with obesity who lost weight compared with individuals who had stable non obesity; however, weight loss was rare, and the association was not statistically significant. If those who no longer had obesity during the 10-year period, it is estimated that 9.1% of observed diabetes cases could have been averted, and if the population had maintained a normal BMI during the period, 64.2% of cases could have been averted. This study used a novel application of NHANES survey data to explore the associations and implications of weight change from young adulthood through midlife and demonstrated the variability of using historic self-reported weight data for longitudinal analyses.
Evidence was found in support of the residual risk hypothesis. Those who had obesity at age 25 then no longer had obesity had an HR of 1.47 relative to those who maintained a non-obese BMI throughout the period. However, the 95% CIs were wide because weight loss from an obese BMI to a non-obese BMI was rare, representing only 1.1% of the total population.
“In testing the risk reduction hypothesis, it was found those who lost weight between young adulthood and midlife showed statistically significant reductions in risk for diabetes onset compared with those who remained obese,” they wrote. When considering the residual risk hypothesis, those who had obesity at age 25 but who subsequently lost weight so that they no longer had obesity had a higher risk of developing diabetes than those who remained without obesity throughout their life, but the difference was not statistically significant. A large percentage of the observed diabetes cases could have been averted with effective intervention and prevention efforts in young adulthood.
The results are consistent with several previous studies that examined weight change in adulthood. A recent study by Zheng et al. found that increasing levels of weight gain were strongly associated with incident diabetes and that moderate weight loss was associated with reduced risk. Among women in the Nurses’ Health study, those who gained 20 kg of weight from early to middle adulthood showed 10.51 times the incidence rate of diabetes compared with those who lost or gained 2.5 kg. Similar effects were observed among men in the Health Professionals Follow-Up study. A similar effect from weight gain was also found in the study, with those gaining into the obese category having 5.77 times the incidence rate of diabetes compared with those who maintained a normal BMI. In an earlier analysis of the Health Professionals Follow-Up study, an elevated BMI of 23 at age 21 was associated with diabetes onset later in adulthood, and a weight gain of 2.5 kg in adulthood was associated with an elevated risk of diabetes. These findings support the results from the study that those who lost weight during the study period did not fully reduce their risk of diabetes relative to those who maintained a non-obese or normal BMI.
The findings from this study underscore the importance of population-level approaches to the prevention and treatment of obesity across the life of individuals.
- Those who lost weight between young adulthood and midlife showed statistically significant reductions in risk for diabetes onset.
- Intervention in young childhood can help to improve quality of life in later life.
Diabetes Care 2018 Mar; dc172336. https://doi.org/10.2337/dc17-2336