Association of insulin and insulin propeptides with an atherogenic lipoprotein phenotype

Lipid and glucose alterations in perinatally-acquired HIV-infected adolescents and young adults

Background

Successful antiretroviral therapy (ART) has dramatically reduced mortality among HIV-infected children. However, there is growing concern about long-term effects associated to ART. The aim of this study was to determine the prevalence of metabolic abnormalities in a cohort of perinatally HIV-infected adolescents and young adults and to identify associated factors.

Methods

We present results from a cross-sectional analysis including individuals 12 to 20 years of age, from a prospective, longitudinal cohort of perinatally-acquired HIV-infected children, adolescents and young adults in Madrid. Clinical and immunological data were recorded and complete lipid and glycemic profiles were determined.

Results

Ninety-nine adolescents were included, with a median age of 15.3 years [13.6-16.7]. Patients with abnormal levels of lipids were as follows: 27.2% total cholesterol ≥200 mg/dl, 25.9% LDL cholesterol (LDL-c) ≥ 130 mg/dl, 14.1% HDL-C < 35 mg/dl and 39.8% triglycerides ≥ 150 mg/dl. Current use of protease inhibitors (PI) was associated with higher triglyceride values (p = 0.022). Four (4.6%) patients showed fasting glucose ≥ 100 mg/dl and 30.6% presented with insulin resistance (IR) (HOMA-IR over the 90th centile). In the multivariate logistic regression analysis adjusted for sex, age, weight, Tanner stage, protease inhibitors (PI) and nucleoside reverse transcriptase inhibitors (NRTI) treatment length and CD4 nadir, IR was associated with higher waist circumference Z score; OR: 3.92(CI95%: 1.15-13.4) (p = 0.03).

Conclusion

There was a high prevalence of insulin resistance and lipid abnormalities in this cohort of perinatally-acquired HIV-infected adolescents. A simple clinical measurement like waist circumference Z score might be a reliable marker and predictor of insulin resistance in these patients.

Characterisation of subjects with early abnormalities of glucose tolerance in the Stockholm Diabetes Prevention Programme: the impact of sex and type 2 diabetes heredity

AIMS/HYPOTHESIS

We evaluated the impact of sex and type 2 diabetes heredity on the prevalence and pathogenesis of early abnormalities of glucose homeostasis in subjects participating in the Stockholm Diabetes Prevention Programme.

METHODS

A sample of 3,128 men and 4,821 women, of whom approximately half had a family history of type 2 diabetes (FHD) was categorised according to an OGTT: NGT, IFG, IGT, combined glucose intolerance and type 2 diabetes. The homeostasis model assessment was used to determine insulin sensitivity and beta cell function.

RESULTS

Prevalence of early abnormalities of glucose metabolism was two to three times higher in subjects with FHD and two to three times higher in men compared to women. Both maternal and paternal heredity of type 2 diabetes were associated with an increased risk of having early abnormalities of glucose metabolism. However, in women with type 2 diabetes heredity on the father's side seems to have less impact on an increased risk of having type 2 diabetes. Both waist circumference and systolic blood pressure were increased in subjects with abnormalities of glucose homeostasis, whereas insulin sensitivity and beta cell function were decreased. Subjects with IFG had more pronounced impairment of beta cell function and insulin sensitivity than subjects with IGT.

CONCLUSION/INTERPRETATION

An FHD and male sex increased the prevalence of abnormalities of glucose homeostasis. Subjects with IFG had more pronounced defects of insulin secretion and action than subjects with IGT.

Clinical impact of HIV-related lipodystrophy and metabolic abnormalities on cardiovascular disease

Metabolic complications and altered fat distribution associated with HIV infection and antiretroviral therapy may lead to accelerated coronary artery disease (CAD). The high prevalence of multiple cardiovascular risk factors in a significant number of HIV patients is a cause for concern in both patients and physicians. Non-invasive strategies to measure subclinical CAD have been inconclusive. Long-term studies are underway to determine cardiac event rates, intervention strategies and consequences for the clinical management of HIV disease. In the present paper, we summarize the most prevalent risk factors in individuals with HIV infection receiving highly active antiretroviral therapy by focusing on the clinical implications of metabolic abnormalities and HIV-related lipodystrophy on CAD.

The role of non-LDL:non-HDL particles in atherosclerosis

Elevated concentrations of circulating apolipoprotein B (apoB)-containing lipoproteins, other than low-density lipoprotein (LDL), have been implicated as causative agents for the development of atherosclerosis. A form of dyslipidemia, the atherogenic lipoprotein profile, that consists of elevated intermediate-density lipoprotein (IDL), triglycerides (TGs), dense LDL and dense very low density lipoprotein (VLDL), and low high density lipoprotein-2, occurs in 40% to 50% of patients with coronary artery disease (CAD). The recently released Adult Treatment Panel III guidelines suggest that because elevated TGs are an independent CAD risk factor, some TG-rich lipoproteins, commonly called remnant lipoproteins, must be atherogenic. Relevant to this series on diabetes, a number of studies have shown that in type 2 diabetes, the severity of CAD is positively related to the numbers of TG-rich particles in the plasma. Although less clear, other studies in type 2 diabetes suggest that elevated levels of lipoprotein (a) [Lp(a)] may also be independently associated with CAD. In this article, we summarize evidence for the role of apoB-containing lipoprotein particles other than LDL in the development of atherosclerosis and discuss methods of quantification and possible pharmacologic interventions for lowering their plasma concentrations. The particles reviewed include the TG-rich lipoproteins: VLDL and its remnants, chylomicron remnants and IDL, and the C-rich lipoprotein: Lp(a).

Insulin sensitivity and fertility

This review sets in context significant recent advances in the understanding of the pathophysiology of polycystic ovary syndrome (PCOS). The occurrence of variable insulin sensitivity in individuals is discussed. Information is presented to demonstrate that prolonged anovulation decreases insulin sensitivity and, conversely, that improvement in insulin sensitivity normalizes ovarian function in PCOS. In addition, a meta-analysis of studies on metformin and troglitazone treatment in PCOS is presented.

Impaired glucose tolerance, beta cell function and lipid metabolism in HIV patients under treatment with protease inhibitors

OBJECTIVES

To evaluate metabolic abnormalities, beta-cell function, lipid profile and vascular risk factors in HIV patients on protease inhibitors (PI).

DESIGN

Prospective cross-sectional study.

METHODS

Thirty-eight HIV-1-infected patients receiving at least one PI were compared with 17 PI-naive HIV patients in an oral glucose tolerance test (OGTT). Serum glucose, insulin, proinsulin, and C-peptide were determined. The fasting lipid pattern was analysed using electrophoresis and the assessment of apolipoproteins including lipoprotein (a). Fibrinogen, homocysteine, and anticardiolipin antibodies were also assessed.

RESULTS

Twenty-seven (71%) of the PI-treated group had detectable hyperlipidaemia. Isolated hypertriglyceridaemia was present in 12 patients (44%), two (7%) of them had type V and 10 (37%) subjects had type IV hyperlipidaemia (Frederickson classification). Type IIb hyperlipidaemia defined as an increase of both very-low-density lipoproteins (VLDL) and low-density lipoproteins (LDL) was found in 10 (36%) subjects, and five (18%) patients presented with isolated hypercholesterolaemia (type IIa). PI treatment was associated with significant higher fasting cholesterol, triglycerides, LDL and VLDL levels. Apolipoprotein B and E concentrations were significantly increased in patients receiving PI. Elevated concentrations of lipoprotein (a) (> 30 mg/dl) were detected in six (16%) of the hyperlipidaemic patients on PI. Eighteen (46%) patients on PI had impaired oral glucose tolerance and five (13%) had diabetes. Although four (24%) of the PI-naive patients were glucose intolerant, none had diabetes. Fasting concentrations and secretion response of insulin, proinsulin, and C-peptide to glucose ingestion was significantly increased in the PI-treated group suggesting a beta-cell dysfunction in addition to peripheral insulin resistance. Beta-cell abnormalities were associated with the abnormal lipid pattern and PI treatment.

CONCLUSION

Combination drug regimens including PI are accompanied by impaired glucose tolerance, hyperproinsulinaemia as an indicator for beta-cell dysfunction, and lipid abnormalities proved to be significant risk factors for coronary heart disease. Moreover, PI may have an impact on the processing of proinsulin to insulin.