Left ventricular mass is not related to insulin sensitivity in never-treated primary hypertension

Insulin has been suggested to promote myocardial cell growth and the development of left ventricular (LV) hypertrophy. This study examines the possible relationship between LV mass and insulin sensitivity.

Previously untreated non-diabetic hypertensive patients.

Fifty-one patients with mean age 51 +/- 8 years, body mass index (BMI) 25.9 +/- 3.2 kg/m2 and blood pressure 158/102 mmHg were included. LV mass was determined by echocardiography. Glucose metabolism was assessed by an euglycemic insulin clamp (40 mU/m2 body surface area/min).

Insulin sensitivity index (MI) and insulin clearance were inversely related to LV mass (r = -0.37, P < 0.01 and -0.33, P < 0.05, respectively) and LV mass indexed to height (r = -0.33, P < 0.05 and -0.29, P < 0.05, respectively). C-peptide and fasting insulin were related to LV mass (r = 0.33, P < 0.05 and r = 0.36, P < 0.01, respectively) and LV mass indexed to height (r = 0.30, P < 0.05 and r = 0.34, P < 0.05, respectively). In contrast, when LV mass was indexed by body surface area there was no longer a relation to MI, insulin clearance, C-peptide or fasting insulin. When adjusting for BMI in a multiple regression analysis, MI and LV mass no longer showed a relation. Indeed, MI, insulin clearance, C-peptide and insulin were all strongly related to weight and BMI.

Insulin sensitivity is related to body size in untreated hypertension. However, insulin sensitivity is not related to LV mass, if adjusting for body size. This does not support a direct growth-promoting effect of insulin on the myocardium. Insulin does not appear to be strongly involved in development of hypertensive LV hypertrophy.