BACKGROUND Obesity precedes the development of type 2 diabetes (T2D). However, the relationship between the magnitude and rate of weight gain to T2D development and complications, especially in non-White populations, has received less attention.

METHODS AND FINDINGS We determined the association of rate and magnitude of weight gain to age at T2D diagnosis (Age(T2D)), HbA1c at T2D diagnosis (HbA1c(T2D)), microalbuminuria, and diabetic retinopathy after adjusting for sex, BMI at age 20 years, lifestyles, family history of T2D and/or blood pressure and lipids in 2164 Korean subjects aged ≥30 years and newly diagnosed with diabetes. Body weight at age 20 years (Wt(20y)) was obtained by recall or from participants' medical, school, or military records. Participants recalled their maximum weight (Wt(max)) prior to T2D diagnosis and age at maximum weight (Age(max_wt)). The rate of weight gain (Rate(max_wt)) was calculated from magnitude of weight gain (ΔWt = Wt(max)-Wt(20y)) divided by ΔTime (Age(max_wt) -20 years). The mean Age(max_wt) and Age(T2D) were 41.5±10.9 years and 50.1±10.5 years, respectively. The Wt(20y) and Wt(max) were 59.9±10.5 kg and 72.9±11.4 kg, respectively. The Rate(max_wt) was 0.56±0.50 kg/year. After adjusting for risk factors, greater ΔWt and higher Rate(max_wt) were significantly associated with earlier Age(T2D), higher HbA1c(T2D) after additional adjusting for Age(T2D), and microalbuminuria after further adjusting for HbA1c(T2D) and lipid profiles. Greater ΔWt and higher Rate(max_wt) were also significantly associated with diabetic retinopathy.

CONCLUSIONS This finding supports public health recommendations to reduce the risk of T2D and its complications by preventing weight gain from early adulthood.