Research

Mixed

In patients with type 2 diabetes, being overweight (BMI 25–29.9 kg/m²) is associated with a lower all-cause mortality risk compared to normal weight (BMI 18.5–24.9 kg/m²), whereas obesity (BMI >30 kg/m²) confers no mortality benefit and increases cardiovascular event risk.

If you have type 2 diabetes, being overweight (BMI 25-29.9) is associated with better survival than being normal weight (BMI 18.5-24.9). Obesity (BMI >30) does not increase mortality risk compared to normal weight, though it does increase cardiovascular events. Do not use this to justify obesity, but understand that extreme thinness in T2D is a high-risk state. Focus on fitness and managing comorbidities rather than aggressive weight loss alone, especially if you are already lean.

GoodQualifiesHIGH confidence
being overweight was associated with a lower mortality risk, whereas obese patients (BMI >30 kg/m2) had a mortality risk similar to that of normal-weight persons. Patients with low body weight had the worst prognosis.
Pierluigi Costanzo et al. · Annals of Internal Medicine · 2015

Why this rating

Large prospective cohort (n=10,568), long follow-up (median 10.6 years), adjusted for major confounders, but observational design limits causal inference.

Source

The Obesity Paradox in Type 2 Diabetes Mellitus: Relationship of Body Mass Index to Prognosis

Pierluigi Costanzo et al. · Annals of Internal Medicine · 2015

DOI 10.7326/m14-1551

cohort · n=10568Cited 196×
Read the paper
DOI resolved against Crossref · corpus check 2026-06-10

This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →