Hyperinsulinemia in hypertension: increased secretion, reduced clearance or both?

Area of Science:

• Endocrinology
• Cardiovascular Medicine
• Metabolic Syndrome

Background:

• Peripheral hyperinsulinism is a potential factor in hypertension development, but evidence linking insulin and blood pressure is inconsistent.
• Understanding the relationship between insulin resistance and hypertension is crucial for metabolic and cardiovascular health.

Purpose of the Study:

• To prospectively investigate glucose metabolism, insulin, C-peptide, and serum lipids in hypertensive versus normotensive subjects.
• To clarify the association between insulin resistance markers and blood pressure in a large cohort.

Main Methods:

• Prospective study comparing 145 hypertensive subjects with 132 age and body mass index (BMI)-matched normotensive controls.
• Measurements included fasting plasma insulin, C-peptide, glycated hemoglobin A1c (HbA1c), serum lipids, and blood pressure.
• Insulin sensitivity was estimated using the HbA1c/insulin ratio.

Main Results:

• Hypertensives showed significantly elevated fasting insulin and LDL-cholesterol compared to normotensives.
• The HbA1c/insulin ratio, indicating insulin sensitivity, was significantly lower in hypertensives.
• No significant correlation was found between mean blood pressure and fasting insulin, C-peptide, or insulin sensitivity markers.
• Obese hypertensives with impaired glucose tolerance displayed the lowest insulin sensitivity and clearance.

Conclusions:

• Hypertension is associated with impaired insulin sensitivity and elevated fasting insulin levels.
• Despite group differences, individual blood pressure did not correlate with markers of insulin metabolism in this cohort.
• Further research is needed to elucidate the complex interplay between insulin resistance and hypertension pathogenesis.