Very-low-calorie diet: a quick therapeutic tool to improve β cell function in morbidly obese patients with type 2 diabetes.
BACKGROUND
Caloric restriction in obese diabetic patients quickly improves glucose control, independently from weight loss. However, the early effects of a very-low-calorie diet (VLCD) on insulin sensitivity and insulin secretion in morbidly obese patients with type 2 diabetes are still unclear.


OBJECTIVE
The objective was to study the relative contributions of insulin sensitivity, insulin secretion, or both to improvement in glucose metabolism, after 1 wk of caloric restriction, in severely obese diabetic patients.


METHODS
Hyperglycemic clamps were performed in 14 severely obese (BMI, in kg/m(2): >40) patients with type 2 diabetes in good glucose control (glycated hemoglobin < 7.5%) before and after 7 d of a VLCD (400 kcal/d).


RESULTS
The VLCD caused a 3.22 ± 0.56% weight loss (P < 0.001), 42.0% of which was fat loss, accompanied by decreases in fasting plasma glucose (P < 0.05) and triglycerides (P < 0.01). In parallel, the Disposition Index, which measures the body's capability to dispose of a glucose load, increased from 59.0 ± 6.3 to 75.5 ± 6.3 mL· min(-1) · m(-2) body surface area (P < 0.01), because of improvements in indexes of both first- and second-phase insulin secretion (P < 0.02), but with no changes in insulin sensitivity (P = 0.33).


CONCLUSIONS
The marked improvement in metabolic profile, observed in severely obese patients with type 2 diabetes after a 7-d VLCD, was primarily due to the amelioration of β cell function, whereas no contribution of insulin sensitivity was shown. This trial was registered at www.clinicaltrials.gov as NCT01447524.
Department of Medicine, University of Rome Tor Vergata, Rome, Italy.
Ilaria
I
Malandrucco
Patrizio
P
Pasqualetti
Ilaria
I
Giordani
Dario
D
Manfellotto
Federica
F
De Marco
Filippo
F
Alegiani
Anna Maria
AM
Sidoti
Fabiana
F
Picconi
Alessandra
A
Di Flaviani
Gaetano
G
Frajese
Riccardo C
RC
Bonadonna
Simona
S
Frontoni
D000284:Administration, Oral; D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D031204:Caloric Restriction; D002784:Cholesterol / Q000097:blood; D003404:Creatinine / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000178:diet therapy* / Q000503:physiopathology; D002149:Energy Intake; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage; D007328:Insulin / Q000097:blood / Q000378:metabolism; D007333:Insulin Resistance; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000150:complications / Q000178:diet therapy* / Q000503:physiopathology; D014280:Triglycerides / Q000097:blood; D015431:Weight Loss
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D014280:Triglycerides; D002784:Cholesterol; D003404:Creatinine