Lars Lind

Left Ventricular Concentric Remodeling Rather Than Left Ventricular Hypertrophy Is Related to the Insulin Resistance Syndrome in Elderly Men

BACKGROUND Associations between left ventricular (LV) geometry and the insulin resistance syndrome have been found, mostly in small studies of middle-aged hypertensives. The purpose of this study was to elucidate these associations through the use of a large sample of elderly men. METHODS AND RESULTS We investigated 475 men (157 hypertensives) 71 years of age who were attending a population-based health survey in Uppsala County with echocardiography, oral glucose tolerance test (OGTT), hyperinsulinemic euglycemic clamp, and lipid and 24-hour ambulatory blood pressure monitoring. LV relative wall thickness was significantly related to clamp insulin sensitivity index (r=-0.14), fasting insulin, 32-33 split proinsulin, triglycerides, nonesterified fatty acids, OGTT glucose and insulin levels, waist-to-hip ratio, body mass index, 24-hour blood pressure, and heart rate (r=0.10 to 0.22). Only 24-hour systolic pressure (r=0. 15), OGTT 2-hour insulin (r=-0.10), and heart rate (r=-0.14) were significantly related to LV mass index. Comparing subjects with various LV geometry (normal, concentric remodeling and concentric and eccentric hypertrophy) showed that 24-hour heart rate, OGTT glucose and insulin levels, waist-to-hip ratio, and body mass index were significantly higher (P<0.001 to 0.05) and clamp insulin sensitivity index was significantly lower (P<0.01) in the concentric remodeling geometry group than in the normal LV geometry group. The 24-hour blood pressure was significantly higher in the concentric hypertrophy group than in the normal LV geometry group (P<0.001). CONCLUSIONS Several components of the insulin resistance syndrome were related to thick LV walls and concentric remodeling but less to LV hypertrophy in this population-based sample of elderly men.

Differences in insulin sensitivity and risk markers due to gender and age in hypertensives.

Men run a higher risk for cardiovascular disease than women, even if hypertensive. This has been attributed to a more pronounced central (abdominal) fat distribution in men as well as menopausal state in women. The hypothesis to be tested in hypertensives was that men have more pronounced insulin resistance and other cardiovascular risk factors than pre-menopausal, but not post-menopausal, women. We carried out a cross-sectional observation study of middle-aged hypertensives of both sexes, divided into two age groups, below or over 50 years of age. The study was performed in untreated out-patients, visiting a hypertension policlinic, in Uppsala, Sweden. Three hundred men and 170 women with a mean age of 57 years were investigated. Measurements were taken by: physical examination (body mass index, waist-to-hip ratio, blood pressure); intravenous glucose tolerance test (IVGTT); euglycaemic hyperinsulinaemic clamp; and blood sampling for lipoprotein lipid fractions, uric acid, and free fatty acids. The results were that pre-menopausal women showed a higher insulin-mediated glucose disposal (7.6 vs5.8 mg/kg/min; P < 0.01), and lower fasting glucose (4.9 vs 5.2 mmol/l; P < 0.05) than men, as well as a more advantageous lipoprotein profile. however, in post menopausal women insulin sensitivity decreased and the lipoprotein profile deteriorated. women still showed higher levels of high-density lipoprotein (hdl)-cholesterol, and men a higher waist-to-hip ratio and levels of uric acid, in both age groups. it was concluded that post-menopausal hypertensive women are relatively more insulin resistant than pre-menopausal ones in comparison with men in the same age group and with the same degree of overall obesity.

Insulin resistance in essential hypertension is related to plasma renin activity.

A high plasma renin activity (PRA) has previously been related to several cardiovascular risk factors as well as to later cardiovascular events. As insulin resistance has been suggested as the unifying factor in the insulin resistance metabolic syndrome, insulin resistance was evaluated by the euglycaemic hyperinsulinaemic clamp technique in 50 untreated hypertensive subjects in whom PRA and serum aldosterone were measured together with lipids and an intravenous glucose tolerance test (IVGTT). PRA was inversely related to insulin-mediated glucose disposal during the clamp (r = −0.31, P < 0.05), as well as to fasting insulin (r = 0.32, P < 0.05) and to insulin at 60 min at the ivgtt (r = 0.30, P < 0.05), but not to other risk factors. serum aldosterone was not related to any of the metabolic risk factors. in conclusion, the present investigation showed that insulin resistance is associated with elevated levels of pra in patients with untreated essential hypertension. it thus seems as if a high activity in the renin system should be included in the disturbances included in the insulin resistance metabolic syndrome, a syndrome with a major impact on future cardiovascular events.