To determine the prevalence of fibromyalgia in diabetes mellitus and obesity, 121 consecutive patients have been observed: 27 with obesity (6 males and 21 females; mean age 57 years, range 20-57; mean body mass index [BMI] 34); 88 with type 2 diabetes mellitus (T2DM; 40 males and 48 females; mean age 63 years, range 44-78; mean BMI 28.8; mean glycated haemoglobin [HbA1c] in the last year 8.3%); 6 with type 1 diabetes mellitus (T1DM; 2 males and 4 females; mean age 52 years, range 26-76; mean BMI 24.5; mean HbA1c < 7%). An original questionnaire has been proposed (answer yes/not) as follows: 1) chronic (more than 3 months) and diffuse musculoskeletal pain; 2) sleep disturbances; 3) generalized fatigue; 4) paresthesias at the extremities; 5) swollen impression at hands and feet; 6) symptoms referred to irritable bowel syndrome; 7) headache; 8) symptoms change related with environmental climatic variations and/or exercise. A chronic and diffuse musculoskeletal pain has been reported by 62% of patients as well as in 9% of patients 11/18 positive tender points have been documented. In the patients with a BMI less that 26 the diagnosis of fibromyalgia was negative. Our data seem to reveal the presence of a significant clinical association between obesity, diabetes mellitus and fibromyalgia.