Effect of Weight Change on Type 2 Diabetes Risk: A Prospective Study in a Japanese Population

Although weight reduction has been shown to reduce type 2 diabetes risk, the threshold of weight change, including increase and decrease, associated with the risk remained unclear.

We investigated the association between weight change and the risk of type 2 diabetes.

The participants were 41 539 nondiabetic residents (16 914 men, 24 625 women) in Kochi, Japan, who underwent health examinations between April 2013 and March 2015. The association between 1-year weight change and the risk of type 2 diabetes was assessed using Cox proportional hazards models.

During a mean 5.7-year follow-up, 3564 new-onset type 2 diabetes cases were documented. Compared with participants with stable body weight (<1.0% change), those with weight decreases of 1.0% to 2.9%, 3.0% to 4.9%, and 5.0% or greater showed a lower risk of type 2 diabetes (16% [8%-24%; P < .001]; 25% [15%-34%; P < .001]; and 26% [14%-36%; P < .001], respectively). Conversely, those with weight increases of 1.0% to 2.9%, 3.0% to 4.9%, and 5.0% or greater showed a higher risk (15% [4%-26%; P = .005], 35% [20%-53%; P < .001], and 51% [29%-76%; P < .001], respectively). These associations persisted among individuals with a body mass index (BMI) of 25 or greater or a 10-kg or greater weight gain since age 20 years. Among individuals with BMI 22 to 25, a weight increase of 3.0% or greater showed a higher risk. No associations were observed in individuals with a BMI of less than 22 or aged 75 or older.

Both preventing weight gain and reducing weight are important for lowering the risk of type 2 diabetes in Japanese individuals, particularly among those with a BMI of 22 or greater.