Patients with Cushing's disease (CD) mainly die because of cardiovascular accidents. The aim of this study was to evaluate whether patients with CD still have increased cardiovascular risk and suffer from premature atherosclerosis once cured. Fifteen patients cured from CD for a long term period (5 yr), 30 sex-and age-matched controls, and 30 body mass index (BMI)-matched controls were included in this study. BMI; waist to hip ratio (WHR); systolic (SBP) and diastolic (DBP) blood pressures; serum total, low density lipoprotein (LDL), and high density lipoprotein (HDL) cholesterol; serum triglycerides, fibrinogen, and lipoprotein(a) levels; prothrombin time; activated partial thromboplastine time; and basal and glucose load-stimulated insulin and glucose levels were measured in patients and controls. By echo-Doppler ultrasonography, the intima media thickness (IMT), systolic and diastolic media-media distances, blood systolic (SPV) and diastolic (DPV) peak velocity, systolic (SLD) and diastolic (DLD) lumen diameter, and distensibility coefficient (DC) were measured at both common carotid arteries where the presence, size, and location of atherosclerotic plaques were also evaluated. Compared with a sex- and age-matched control population, CD patients had BMI (P < 0.001), WHR (P < 0.001), SBP (P < 0.005), DBP (P < 0.05), fasting glucose (P < 0.001) and insulin (P < 0.05), glucose load-stimulated glucose and insulin levels (P < 0.05), total cholesterol (P < 0.05), LDL cholesterol (P < 0.01), fibrinogen (P < 0.01), and lipoprotein(a) (P < 0.05) levels higher and HDL cholesterol levels (P < 0.05) lower than controls. At ultrasonography, in the patients, IMT (P < 0.05), SPV (P < 0.05) and DPV (P < 0.001) were significantly increased whereas SLD (P < 0.001), DLD (P < 0.001), and DC (P < 0.05) were significantly decreased compared to controls. In addition, CD patients had higher WHR (P < 0.05), DBP (P < 0.05), glucose load-stimulated glucose and insulin levels (P < 0.05), and fibrinogen levels (P < 0.01) and lower HDL cholesterol (P < 0.05) levels than BMI-matched controls. At ultrasonography, increased common carotid arteries IMT (P < 0.05) and DPV (P < 0.05) and decreased DLD (P < 0.05) and DC (P < 0.05) were measured in patients compared to those in BMI-matched controls. Atherosclerotic plaques were found in 26.7% of patients, in none of the sex- and age-matched controls, and in 3.3% of the BMI-matched controls. In CD patients, a significant correlation was found between both WHR and fasting serum insulin levels and DBP (r = 0.52 and r = 0.55; P < 0.05), triglycerides levels (r = 0.56 and r = 0.77; P < 0.05), and IMT (r = 0.64 and r = 0.56; P < 0.05). Right (r = -0.70; P < 0.005) and left (r = -0.65; P < 0.01) DC were inversely correlated to the duration of CD in the patient group. At the multiple regression analysis, WHR was the best predictor of fasting insulin levels (beta = 0.77; P < 0.05), and vice versa, fasting insulin level was the best predictor of WHR (beta = 1.20; P < 0.05). In conclusion, patients cured from CD for a long term period have a high prevalence of atherosclerosis and maintain increased several cardiovascular risk factors of the active disease, probably due to a residual abdominal obesity and/or insulin resistance syndrome.

Persistence of increased cardiovascular risk in patients with Cushing's disease after five years of successful cure.

Cardiovascular accidents represent the most important cause of death in patients with Cushing's syndrome. This prospective study aims at evaluating carotid arteries by echo-Doppler ultrasonography and clinical and metabolic markers of atherosclerosis in 25 patients with Cushing's disease (CD) before and after 1 yr of remission. Thirty-two sex- and age-matched subjects (control-1) and 32 body mass index-matched subjects (control-2) served as controls. At diagnosis, CD patients had higher body mass index, waist to hip ratio (WHR), total, low-density lipoprotein-cholesterol and total/high-density lipoprotein (HDL) ratio, glucose and insulin, as well as lower HDL-cholesterol than control-1; they had higher WHR and total/HDL ratio and lower HDL-cholesterol than control-2. They also had higher intima-media thickness (IMT), and lower systolic lumen diameter and distensibility coefficient (DC) than either control group. Atherosclerotic plaques were detected in 31.2% of patients, 0 control-1, and 6.2% of control-2 subjects. One year after remission, WHR, LDL-cholesterol, and IMT significantly decreased, whereas systolic lumen diameter and DC significantly increased. However, all of the above parameters were still abnormal compared with control-1, but not control-2. A significant correlation was found between WHR, glucose and insulin levels, and right and left carotid IMT. WHR was the best predictor of left IMT and left DC in active, but not in cured, patients. The duration of hypercortisolism was the best predictor of right DC in active but not in cured patients. In conclusion, patients with CD have severe atherosclerotic damage. The persistence of a metabolic syndrome, vascular damage, and atherosclerotic plaques after cortisol level normalization makes these subjects still at high cardiovascular risk despite disease remission.

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Cardiovascular risk factors and common carotid artery caliber and stiffness in patients with Cushing's disease during active disease and 1 year after disease remission.

https://www.endo.theclinics.com/article/S0889-8529(05)00011-3/pdf

The Metabolic Syndrome and Cardiovascular Risk in Cushing's Syndrome

We have examined insulin action on glucose metabolism in six hypothyroid patients before and after regular thyroid hormone treatment, and in six healthy volunteers before and after transient induction of moderate hyperthyroidism. Insulin was infused under euglycaemic and eukalaemic clamps. An appropriate amino acid infusion was used to blunt insulin-induced decreases in amino acid levels. Glucose kinetics were assessed using a primed continuous infusion of [6,6-(2)H(2)]glucose. The results showed that basal plasma insulin and glucose levels (i.e. before infusion) were similar in each case. Despite similar insulin infusion rates, the plateau value of insulin was lower after thyroid treatment in both hypothyroid patients and healthy volunteers. The rate of exogenous glucose needed to maintain plasma glucose at a steady-state level was increased by thyroid hormone in hypothyroid patients (P <0.05), but not in healthy volunteers. Thyroid treatment resulted in a significant increase in basal glucose disposal in both groups (P <0.05). Insulin, in conjunction with glucose and amino acids, significantly stimulated glucose disposal (P <0.05) under all conditions. The incremental increase in glucose disposal after infusion tended to be higher following thyroid hormone treatment, but this was not statistically significant. However, the ratio of the incremental increase in glucose disposal to the increase in plasma insulin was significantly improved after thyroid hormone treatment in hypothyroid patients (P <0.05). It was also increased in healthy volunteers, but not significantly. We conclude that thyroid hormones improve the ability of insulin to stimulate glucose disposal related to insulinaemia. This phenomenon may be highly sensitive, because it was only apparent at low thyroid hormone levels.

Response of glucose disposal to hyperinsulinaemia in human hypothyroidism and hyperthyroidism.

Excess cortisol has been demonstrated to impair hepatic and extrahepatic insulin action. To determine whether glucose effectiveness and, in terms of endogenous glucose release (EGR), gluconeogenesi...

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Impaired basal glucose effectiveness but unaltered fasting glucose release and gluconeogenesis during short-term hypercortisolemia in healthy subjects

Insulin resistance is well established in Cushing's syndrome, but its mechanisms are not completely understood. We performed the euglycemic insulin clamp technique on four patients with Cushing's syndrome, five obese patients and five normal volunteers, in order to determine the role of impairments in insulin responsiveness and insulin clearance in hypercorticism and obesity. Insulin was infused at 0.3, 1, 3 and 10 mU/kg/min, and steady-state glucose-infusion rates required to maintain euglycemia were determined. Glucose disposal at maximal insulin levels was 11.9 +/- 0.4 mg/kg/min in normals, with a 29% decrease in obese and a 42% decrease in Cushing's syndrome patients. Half maximally effective insulin concentrations were increased in both abnormal groups compared to normals. Maximal insulin clearance rates were 1460 +/- 200 ml/min/m2 in normals, not significantly changed in obese and 40% decreased in Cushing's syndrome patients. These results indicate that the insulin resistance in Cushing's syndrome is distinct from that occurring in obesity and is characterized by both decreased insulin responsiveness and decreased insulin clearance. These impairments could be caused by a common defect which may be at or distal to the glucose transport level.

Insulin resistance in Cushing's syndrome.

Insulin is known to decrease plasma levels of both glucose and amino acids. We have designed a study to examine whether in hyperthyroidism, where insulin sensitivity is changed, correlation between glucose disposal and amino acids levels is maintained. We studied 5 normal (N) and 5 hyperthyroid (HTD) subjects, and measured glucose disposal rate and serum levels of plasma amino acids before and during insulin infusion utilizing the euglycemic hyperinsulinemic clamp technique. Insulin was effective in decreasing the levels of all amino acids in the plasma of all subjects. The mean amino acid decrease in response to insulin infusion rate of 10 mu/kg/min was 35 +/- 3% in N and 50 +/- 3% in HTD. The half maximally effective dose of insulin on glucose disposal was 43 +/- 3 and 69 +/- 9 uU/ml in N and HTD respectively (p < 0.05). The half maximally effective dose of insulin on decreasing plasma amino acids was 37 +/- 7 and 75 +/- 5 uU/ml in N and HTD respectively (p < 0.01). The concentration of insulin giving a half maximal effect on serum amino acids correlated with the half-maximally effective dose on glucose disposal rate (r = 0.72, p < 0.01). The maximal effect on total amino acid levels correlated with maximal glucose disposal (r = 0.76, p < 0.001). Similar results were observed with branched chain amino acids. We conclude that in hyperthyroidism glucose disposal and decrease in amino acids levels are closely correlated as in healthy subjects. This also confirms the association between glucose disposal and amino acids levels in a variety of insulin sensitive and resistant states.

D. Barzilai

Papers

Insulin resistance in Cushing's syndrome.

Correlation between glucose disposal and amino acids levels in hyperthyroidism