Insulin hypersecretion: a distinctive feature between essential and secondary hypertension

Area of Science:

• Endocrinology
• Cardiovascular Medicine
• Metabolic Syndrome

Background:

• Patients with hypertension often exhibit elevated plasma insulin levels compared to normotensive individuals.
• The underlying causes of hyperinsulinemia in hypertension, including pancreatic secretion and hepatic clearance, require further investigation.
• Understanding glucose metabolism abnormalities in different types of hypertension is crucial.

Purpose of the Study:

• To determine if hyperinsulinemia in hypertension results from increased pancreatic secretion or decreased hepatic insulin clearance.
• To assess if glucose metabolism abnormalities are consistent across essential and secondary hypertension.
• To investigate the relationship between blood pressure, body mass index, and insulin/glucose metabolism.

Main Methods:

• An observational cross-sectional study involving five groups: lean normotensive, overweight normotensive, lean essential hypertensive, overweight essential hypertensive, and secondary hypertensive subjects.
• Measurement of fasting blood glucose, plasma insulin, and plasma C-peptide levels.
• Calculation of glucose/insulin and insulin/C-peptide ratios as indices of insulin sensitivity and hepatic insulin clearance.

Main Results:

• Essential hypertensive and overweight subjects showed higher fasting insulin and C-peptide levels and lower glucose/insulin ratios than lean normotensive controls.
• Secondary hypertensive subjects did not differ from controls in these metabolic parameters.
• Mean blood pressure correlated significantly with body mass index, insulin, C-peptide, and the glucose/insulin ratio.

Conclusions:

• In essential hypertension, hyperinsulinemia is primarily due to increased insulin secretion.
• In overweight hypertensive individuals, both increased insulin secretion and potentially decreased hepatic insulin clearance contribute to hyperinsulinemia.
• Hepatic insulin clearance appears normal in lean essential and secondary hypertension but may be reduced in overweight hypertensive subjects.