In patients with CHF, lower S(I) relates to higher mortality, independent of body composition and established prognosticators. Impaired S(I) may have implications in the pathophysiology of CHF disease progression. Therapeutically targeting impaired insulin sensitivity may potentially be beneficial in patients with CHF.

Abstract-In humans, production of the adipocyte-derived peptide leptin has been linked to adiposity, insulin, and insulin sensitivity. We therefore considered that alterations in plasma leptin concentrations could constitute an additional component of a metabolic syndrome of cardiovascular risk. 001).Factor analysis of plasma leptin concentrations and the variables that are considered relevant to the insulin resistance syndrome revealed a clustering of plasma leptin concentrations with a factor dominated by insulin resistance and high IVGTT insulin, separate from a high IVGTT glucose/central obesity factor and a high triglyceride/low high density lipoprotein cholesterol factor. Together, these factors accounted for 55.9% of the total variance in the dataset. In conclusion, interindividual variations in plasma leptin concentrations are strongly related to the principal components of the insulin resistance syndrome. Further studies are needed to determine whether the insulin-leptin axis plays a coordinating role in this syndrome and whether plasma leptin concentrations could provide an additional measure of cardiovascular risk. (Arterioscler Thromb Vasc Biol. 1998;18:928-933.)

We have carried out intravenous glucose tolerance tests with measurement of plasma glucose, insulin and C-peptide concentrations on 66 premenopausal and 92 postmenopausal non-obese caucasian women. After adjustment for the effects of a number of possible confounding variables, including age and body mass index, there was little difference between pre and postmenopausal women in glucose and insulin concentrations either fasting or in response to intravenous glucose. Mathematical modelling analysis of the resultant plasma concentration profiles was used to obtain measures of insulin sensitivity, secretion and elimination, and non-insulin dependent glucose disposal. We found reciprocal differences in mean insulin sensitivity (increased by 50%) and non-insulin dependent glucose disposal (decreased by 30%). Plasma C-peptide response and pancreatic insulin secretion were markedly lower in the postmenopausal group (-35% and -51% respectively). However, the rate constant for insulin elimination was also lower in these women. As a result, intravenous glucose tolerance test plasma insulin concentrations were not significantly different between the two groups. We conclude that, despite the occurrence of little or no variation in plasma glucose and insulin concentrations, the menopause is associated with significant changes in insulin metabolism.

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This study shows that young, nondiabetic, male survivors of myocardial infarction are truly hyperinsulinemic during an OGTT and suggests a close association between proinsulin and coronary atherosclerosis.

Summary Whether hormone replacement therapy (HRT) is beneficial for coronary heart disease (CHD) is controversial. We hypothesized that continuous combined transdermal HRT may have benefits on CHD risk markers without the potential adverse effects seen with certain other HRT regimens. Sixty apparently healthy postmenopausal women, aged 40–65 years, entered a prospective, double‐blind, randomized, placebo‐controlled clinical trial; 55 women completed the 6‐month study. Women received either transdermal oestradiol 17β 0·05 mg and norethisterone acetate 0·125 mg daily, or identical placebo. Circulating markers of vascular function and remodelling, forearm blood flow, lipids and lipoproteins, glucose and insulin, and haemostatic safety parameters were measured at baseline and after treatment. Compared with placebo after 6 months, HRT administration resulted in decreased E‐selectin (P < 0·01), and angiotensin‐converting‐enzyme (ACE; P = 0·05). Cholesterol (P < 0·05), low‐density lipoproteins (LDL; P < 0·05), high‐density lipoprotein3 (HDL3; P < 0·05) and apolipoproteins AII (P < 0·05) and B (P < 0·05), and fasting insulin (P < 0·05) also decreased in the HRT group. Factor VII coagulation activity decreased (P < 0·01) and plasminogen activator inhibitor‐1 and fibrin D‐dimer increased (P < 0·05) in the HRT group, whilst prothrombin fragment 1 + 2 (P < 0·05) decreased, more so in the placebo group. There were no changes in matrix metalloproteinase (MMP)‐2, or in LDL particle size. This transdermal HRT had beneficial effects on vascular function and CHD risk markers.

Studies of insulin employing the oral glucose tolerance test demonstrate marked differences between the effects of different oral contraceptives, but provide little insight into the underlying disturbances. We investigated the metabolic basis of these disturbances by computer modelling of iv glucose tolerance test glucose, insulin, and C-peptide concentration profiles. Insulin resistance, secretion, and metabolism were evaluated in 296 oral contraceptive users and 95 nonusers. Four estrogen/progestin combinations, with similar estrogen but differing progestin contents, and 1 progestin-only formulation were studied. Effects on iv glucose tolerance test glucose, insulin, and C-peptide concentrations varied according to progestin content, with levonorgestrel-containing combinations having the greatest effect, followed by desogestrel and norethindrone. However, these formulations increased insulin resistance to a similar extent. The progestin-only formulation did not affect insulin resistance. Levonorgestrel combinations increased second phase pancreatic insulin secretion by 60-90%, but did not affect the insulin half-life. The desogestrel combination increased the insulin half-life by 28%, but did not affect insulin secretion. The effects of different combined oral contraceptives on glucose tolerance test glucose, insulin, and C-peptide concentration profiles appears to be due to a combination of estrogen-induced insulin resistance and progestin-associated changes in insulin half-life.