Ibrahim S. Salti

Higher Serum Leptin Level in Women than in Men with Type 1 Diabetes

&NA; Leptin is the protein product of the obese (ob) gene, a lipostatic hormone that contributes to body weight regulation through suppressing appetite and/or stimulating energy expenditure in humans and/or rodents. In humans, serum leptin concentrations are increased in relation to increased body fat content. Studies have shown a higher leptin level in women compared with men. However, the gender influence on serum leptin concentrations has never been evaluated in patients with type 1 diabetes. In this study, serum leptin levels and percentage body fat mass were measured in men and women with type 1 diabetes. Fasting serum leptin levels were higher in women (16.7±11.6 ng/mL) than in men (3.0±1.5 ng/mL; P<0.05) and were independent of exogenous insulin intake and of glucose control. Percentage body fat and fat mass were significant determinants of leptin concentration, whereas age and duration of diabetes were not related to leptin concentration. Subgroups of men (n=12) and women (n=11) with total body fat between 20 and 30% were compared. Leptin levels were also higher in women compared with men (13.5±8.3 ng/mL versus 3.2±1.7 ng/mL; P<0.05, respectively). In conclusion, our findings indicate that gender is an important determinant of serum leptin concentration in type 1 diabetics, this gender difference is partly explained by body fat distribution and that type 1 diabetic women may be more resistant than type 1 diabetic men to leptin’s alleged lipostatic actions.

Leptin levels in patients with Type 1 diabetes receiving intensive insulin therapy compared with those in patients receiving conventional insulin therapy

Several reports suggest that insulin may have a role in the regulation of serum leptin levels, and this is related to the fact that serum leptin levels generally indicate the amount of body fat. Studies show that leptin levels are low in newly diagnosed patients with Type-1 diabetes (T1DM) and increase after institution of insulin therapy. This study was designed to test whether serum leptin levels are higher in patients receiving intensive insulin therapy (IIT) compared to conventional insulin therapy (CIT). Young patients with T1DM were studied, 23 on IIT and 23 on CIT. The patients were matched for age (19±3 and 20±5 yr, respectively), duration of diabetes (8±5 and 10±6 yr, respectively) and BMI (24±4 and 23±3 kg/m2, respectively). Leptin levels were higher in IIT compared to CIT (13±12 vs 7±7 ng/ml, respectively, p<0.05). The results of this study demonstrate that patients on IIT have higher leptin levels than patients on CIT. This increase in leptin level in IIT patients is independent of changes in bw and is probably due to the stimulatory effect of insulin on leptin production.

Hypercalciuric Rickets: a rare cause of Nephrolithiasis

An unusual case of rickets associated with hypercalciuria is described. In addition to proteinuria, the patient had phosphaturia, aminoaciduria, renal glucosuria and impaired renal concentration but no renal tubular acidosis. Studies did not support the diagnosis of primary hyperparathyroidism. The findings in the patient were very similar to those in 4 previously reported cases and are suggestive of a new combination of multiple renal tubular defects.