Insulin secretion in patients with diabetes insipidus during long-term treatment with chlorpropamide

The relation between leptin and insulin remains when insulin secretion is disturbed

BACKGROUND

Serum insulin and leptin levels correlate positively. It is not known whether this relation remains the same in cases of severely disturbed insulin secretion and after rapid weight loss. We therefore studied the relation between insulin and leptin in obese type 2 diabetic patients before and after considerable weight loss.

METHODS

In 17 obese type 2 diabetic patients, blood glucose-lowering medication was discontinued (day-1) and a 30-day very low calorie diet (VLCD, 450 kcal/day) was started. On days 0, 2, and 30, body weight, body fat mass [with bioelectrical impedance analysis (BIA)], fasting serum glucose, insulin, and leptin were determined. Homeostatic model assessment was used to estimate insulin resistance (HOMA-IR) and beta-cell function (HOMA-beta). On days 2 and 30, an intravenous glucose tolerance test (IVGTT) was performed.

RESULTS

Fasting serum leptin levels correlated positively with fasting serum insulin levels (r=0.72, p=0.001 on day 2; r=0.78, p=0.001 on day 30) and area under the curve (AUC) of insulin (r=0.74, p=0.001 on day 2; r=0.84, p=0.0001 on day 30), as well as HOMA-beta, as a measure of insulin secretion, even after correction for body mass index (BMI) and body fat mass, with which leptin was also positively correlated.

CONCLUSION

In a group of obese type 2 diabetic patients with a wide range of residual endogenous insulin secretion, we found a positive relation between fasting serum leptin and insulin levels, even after correction for BMI and body fat mass. This was true both before weight loss and during energy restriction with weight loss.

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-beta-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 beta-cells to secrete insulin predicts a favourable metabolic response to a VLCD in obese Type 2 diabetic patients.