Borderline
hypertension is often the initial stage of stabilized
hypertension. This study aimed to provide insight on
insulin behavior and its relationship with
glucose metabolism by investigating insulin secretion and hepatic clearance in non-steady-state conditions in borderline hypertensive patients.
METHODS AND RESULTS: We studied 15 patients (6 F, 9M, 44 +/- 2 yr, 78 +/- 2 kg, systolic pressure 155 +/- 10 mmHg, diastolic 93 +/- 5) and 15 comparable healthy controls. All underwent an intravenous
glucose test, with minimal model analysis to measure
insulin sensitivity S1,
glucose effectiveness SG,
insulin pre-hepatic release, hepatic extraction, and
insulin appearance rate in the systemic circulation. Basal
glucose (3.98 +/- 0.12 vs 3.94 +/- 0.11 mmol/L, hypertensive vs control subjects respectively), i.v.
glucose tolerance factor KG (2.0 +/- 0.2 vs 2.2 +/- 0.1% min-1), SG (0.035 +/- 0.004 vs 0.032 +/- 0.007 min-1) and S1 [3.5 +/- 0.5 vs 3.8 +/- 0.3 10(4) min-1 (microU/mL)] were similar, both basal
insulin and
C-peptide exhibited a marked increase (87 +/- 8 vs 46 +/- 6 pmol/L, p = 0.0003; 637 +/- 62 vs 381 +/- 76 pmol/L, p < 0.03) demonstrating
insulin resistance in basal conditions. Insulin secretion per unit volume was greater in patients, both at basal (43 +/- 5 vs 24 +/- 5 pmol/L/min, p = 0.01) and after stimulation (total
hormone released = 18 +/- 2 vs 11 +/- 2 nmol/L in 4 h, p = 0.022). Post-hepatic
insulin delivery was also elevated (basal = 11 +/- 1 vs 6 +/- 1 pmol/L/min, p < 0.002, total = 5 +/- 1 vs 3 +/- 0.3 nmol/L in 4 h, p = 0.02), while no difference was detected in hepatic extraction (66 +/- 4% vs 66 +/- 3).
CONCLUSION: