Overweight and macrovascular complications in type 1 diabetes: A nationwide registry study (J‑DREAMS)

To test whether overweight (BMI ≥ 25 kg/m²) is associated with macrovascular complications in Japanese adults with type 1 diabetes, and to examine long‑term effects of overweight at age 20.

We retrospectively analyzed 2,181 adults in the J‑DREAMS registry (2016-2023). Participants were classified as overweight or non‑overweight. Primary outcomes were prevalence of coronary artery disease (CAD), cerebrovascular disease (CVD), and peripheral artery disease (PAD); secondary outcomes were microvascular complications and comorbidities. Logistic regression adjusted for key confounders. Among 1,068 with BMI at age 20, we compared those overweight at 20 (n = 124) with those not (n = 944).

CAD was more frequent in the overweight group (8.9 % vs 3.4 %; p < 0.001). Overweight remained independently associated with CAD (adjusted odds ratio 2.41; 95 % CI 1.15-5.06), with no significant associations for CVD or PAD. Overweight was also linked to more neuropathy, nephropathy, hypertension, and dyslipidemia. Prior overweight at age 20 was associated with higher current BMI and HbA1c and more PAD, retinopathy, nephropathy, hypertension, and heart failure.

In Japanese adults with type 1 diabetes, overweight is independently associated with CAD but shows no significant associations with CVD or PAD;overweight in early adulthood tracks with adverse cardiometabolic profiles. Early, sustained weight management with glycemic control may reduce macrovascular risk.