Plasma leptin level does not play an important role on bp regulatory mechanisms in diabetes

Abstract

The objective in the present study was to evaluate the effect of insulin on sympathetic activity, plasma leptin and BP levels. In 8 patients with IDDM, 11 patients with NIDDM and 14 healthy, non-diabetic subjects as a control group (BMI: 23.2, 23.5, 23.1 kg/m2, respectively). BMI, BP, HbA1c, fasting blood glucose, insulin (INS), leptin (LEP) and norepinephrine (NE) were measured at entry, week 4, 12 and 24 during insulin therapy for IDDM or troglitazone for NIDDM. BMI did not change during the study. The subjects were men and without diabetic nephropathy or neuropathy, and untreated for diabetes prior to the present study. The goal of treatments for diabetes was defined as less than 6.5% in HbA1c. At entry, plasma INS and NE were less in IDDM than those in NIDDM and in control group, although LEP was similar to each other (INS: IDDM 3.4*, NIDDM 17.4**, control 8.7 μU/ml, NE: 146*, 179, 171 pg/ml, LEP: 4.8, 4.9, 4.7 ng/ml, *P<0.05 vs control). The patients with IDDM and NIDDM had higher levels in BP than control group at entry (138/86*, 143/89*, 128/75 mmHg). In IDDM treated with insulin administration therapy, BP, INS, LEP, NE increased at week 4, and those elevation remained at week 12 & 24 (week 4: BP 143/90, INS 7.8#, LEP 9.5#, NE 201#, #P<0.05 vs entry). In NIDDM treated with troglitazone, INS decreased at week 12, but BP, LEP nor NE did not change (INS 7.7##, LEP 4.5, NE 165). At week 24, INS and LEP, but not NE nor BP, decreased (INS 7.2##, LEP 3.5#, NE 154, BP). At week 12 and 24, plasma LEP in IDDM was higher than that in control and NIDDM, despite BP level in IDDM was similar to those in NIDDM and higher than that in control group. These results demonstrate that plasma insulin appears to affect plasma leptin level chronically, and that plasma insulin and leptin do not play important roles on BP regulatory mechanisms in diabetic patients.