OBJECTIVE: This study investigates whether fasting plasma glucose (FPG) levels in obese subjects are associated with the number of preadipocytes and their adipokine-secretion capabilities. DESIGN: Abdominal subcutaneous and omental adipose tissues were obtained from 10 female and four male obese subjects (age 37 +/- 8 years; BMI 48 +/- 13 kgm(2)) with a wide range of FPG (range: 4.3-10.6 mm). Stromal vascular cells (SVC) were isolated and cultured and the number of attached SVC (aSVC) per gram adipose tissue determined. The aSVCs were differentiated in vitro to become adipocytes, and the secretion of the adipokine leptin and adiponectin in the culture media was determined. Spearman rank correlation coefficients were calculated between FPG and preadipocyte number and adipokine secretion. PATIENTS: Subject-inclusion criteria: BMI >40 kg/m(2) and for severe comorbid conditions BMI >35 kg/m(2). Subject-exclusion criteria: severe cardiopulmonary pathology (ASA class 3), history of bariatric surgery, manifest psychopathology, 18 years < age > 60 years and for upper-abdominal surgery, age >50 years. All females in the study had regular menstrual periods. None of participants received glucose-lowering medication. RESULTS: No association was observed between BMI and fasting glucose levels. More than 90 +/- 20% of the cultured aSVC fraction was able to store fat droplets, indicating the presence of preadipocytes. A strong negative association was observed between omental preadipocyte number and FPG. A strong association was observed between adipokine secretion by the omental preadipocytes and FPG. No association was observed between subcutaneous preadipocyte number and adipokine secretion and FPG. CONCLUSIONS: In morbid obese subjects, low number of omental preadipocytes with high-leptin- and low-adiponectin-secretion profiles is associated with high FPG.