Factors predicting the blood glucose lowering effect of a 30‐day very low calorie diet in obese Type 2 diabetic patients

Objective  To identify factors which predict the blood glucose lowering effect of monotherapy with a 30‐day very low calorie diet (VLCD) in obese Type 2 diabetic patients. A responder was a priori defined as a patient with a fasting plasma glucose (FPG) level < 10 mmol/l on day 30. Research design and methods  In 17 obese patients (BMI 37.6 ± 5.6 (mean ± SD) kg/m 2 ) with Type 2 diabetes, all blood glucose lowering medication (including insulin) was discontinued on day −1 followed by a 30‐day VLCD. On day 2 and 30 of the VLCD an intravenous glucose tolerance test (IVGTT) was performed. Results  Of the 14 patients who completed the 30‐day VLCD, eight qualified as responder. Responders and non‐responders could be distinguished by day 2. Responders had a shorter duration of Type 2 diabetes and higher fasting serum insulin, C‐peptide and HOMA‐β‐values. In addition, responders displayed a more prominent second‐phase insulin response following i.v. glucose loading and higher k‐values. In a stepwise discriminant analysis, the change in FPG from day 0 to day 2 (responders +0.64 ± 2.3, non‐responders +4.15 ± 3.3 mmol/l, P  = 0.035) in combination with the area under the curve of insulin (AUC) above baseline during an IVGTT on day 2 (responders 571 ± 236, non‐responders 88 ± 65 mU*50 min, P  < 0.001), distinguished responders completely from non‐responders. Conclusion  Preservation of the capacity of β‐cells to secrete insulin predicts a favourable metabolic response to a VLCD in obese Type 2 diabetic patients.