Hyperinsulinemia in patients with hypercholesterolemia.

An independent association between hypercholesterolemia and high insulin levels has not consistently emerged from large-scale epidemiologic observations. We selected 39 patients with elevated low-density (LDL) cholesterol levels but normal body weight, blood pressure, and glucose tolerance, and compared them to 36 normocholesterolemic, healthy control subjects accurately matched to the patients for age, gender, body mass index, and mean arterial blood pressure. Fasting serum total cholesterol concentrations and levels of LDL cholesterol, triglycerides, and apoprotein B were all higher in the patients with hypercholesterolemia than in controls (P < 0.025 or less), whereas high-density lipoprotein cholesterol and apoprotein A levels were significantly lower (P < 0.05 or less). Plasma insulin concentrations were elevated in hypercholesterolemic patients vs. controls both in the fasting state (86 +/- 6 vs. 59 +/- 8 pmol/L) and 2 h after a 75-g oral glucose load (412 +/- 16 vs. 276 +/- 18 pmol/L, P < 0.02 for both). Two-hour plasma glucose concentrations were also significantly raised in the patients (7.8 +/- 0.2 mmol/L) compared to controls (6.4 +/- 0.1 mmol/L, P < 0.025). In a multiple regression model including serum triglyceride concentrations, LDL cholesterol was still significantly related to both fasting and 2-h plasma insulin concentrations, contributing approximately 20% to the overall variability of these measures. Thus, in this group of patients with type IIa familial combined hyperlipoproteinemia hypercholesterolemia was associated with hyperinsulinemia even when controlling for other confounders (age, gender, body mass, glucose tolerance, and blood pressure).     

Clustering of cardiovascular risk factors in confirmed prehypertensive individuals.

Numerous studies have indicated that hypertensive subjects have an atherogenic lipoprotein pattern, hyperinsulinemia, and impaired glucose tolerance relative to normotensive individuals. These abnormalities could be due to adverse effects of certain antihypertensive agents, to pathophysiological concomitants of the hypertensive state itself, or to both. In this report, we describe the cardiovascular risk factor profile of 1,440 subjects who were normotensive and were not taking any antihypertensive medications when first examined and who subsequently participated in the 8-year follow-up of the San Antonio Heart Study. Hypertension developed in 130 subjects during the follow-up period. At baseline these prehypertensive individuals had significantly higher levels of blood pressure, fasting total and low density lipoprotein cholesterol, triglyceride, glucose, and insulin, and 2-hour glucose than those who remained free of hypertension. In addition, they had higher body mass indexes, a less favorable body fat distribution, and lower levels of high density lipoprotein cholesterol. In multiple linear regression analyses, baseline levels of triglyceride and blood pressure remained significantly higher and high density lipoprotein cholesterol remained significantly lower in the subjects who later converted to hypertension than in those who remained normotensive. Although baseline insulin levels were also higher in the prehypertensive subjects, this difference was not statistically significant. In nonobese subjects, however, those with high baseline insulin concentrations had an increased incidence of hypertension compared with those with low insulin concentrations. The present results suggest that the cluster of atherogenic changes associated with hypertension actually precede the development of the hypertensive state.     

Altered pattern of the incretin effect as assessed by modelling in individuals with glucose tolerance ranging from normal to diabetic

Aims/hypothesis

Oral glucose elicits a higher insulin secretory response than intravenous glucose at matched glucose concentrations. This potentiation, known as the incretin effect, is typically expressed as the difference between the total insulin response to oral vs intravenous glucose. This approach does not describe the dynamics of insulin secretion potentiation. We developed a model for the simultaneous analysis of oral and isoglycaemic intravenous glucose responses to dissect the impact of hyperglycaemia and incretin effect on insulin secretion and beta cell function.

Methods

Fifty individuals (23 with normal glucose tolerance [NGT], 17 with impaired glucose tolerance [IGT] and ten with type 2 diabetes) received an OGTT and an isoglycaemic test with measurement of plasma glucose, insulin, C-peptide, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). Our model featured an incretin potentiation factor (P_INCR) for the dose–response function relating insulin secretion to glucose concentration, and an effect on early secretion (rate sensitivity).

Results

In NGT, P_INCR rapidly increased and remained sustained during the whole OGTT (mean P_INCR?>?1, p?<?0.009). The increase was transient in IGT and virtually absent in diabetes. Mean P_INCR was significantly but loosely correlated with GLP-1 AUC (r?=?0.49, p?<?0.006), while the relationship was not significant for GIP. An incretin effect on rate sensitivity was present in all groups (p?<?0.002).

Conclusions/interpretation

The onset of the incretin effect is rapid and sustained in NGT, transient in IGT and virtually absent in diabetes. The profiles of the incretin effect are poorly related to those of the incretin hormones.     

Fixed-dose combination of empagliflozin and linagliptin for the treatment of patients with type 2 diabetes mellitus: A systematic review and meta-analysis

The present meta-analysis evaluated the efficacy and safety of empagliflozin + linagliptin combination compared with either monotherapy [n=6 randomized controlled trials; 2857 adults with type 2 diabetes (T2DM) on diet + exercise ± metformin; 39.7% women; mean age: 54.6–59.9 years]. The combination of empagliflozin 10 mg + linagliptin 5 mg led to significantly greater reductions in glycated haemoglobin (HbA1c) compared with either drug alone over 24 weeks: weighted mean difference [WMD; −0.72%, 95% confidence interval (CI): −1.04, −0.40], and fasting plasma glucose (−1.60 mmol/L 95% CI: −2.21, −1.00). Similar results were observed when empagliflozin 25 mg + linagliptin 5 mg was compared with linagliptin 5 mg monotherapy or with empagliflozin 10 or 25 mg monotherapy. Patients with T2DM treated with the drug combination had more than three times higher likelihood of achieving HbA1c <7% than those on either monotherapy. Weight reduction was significantly greater in the combination group only when compared with linagliptin monotherapy. Safety profile was similar between combination treatment and monotherapies. Overall, the empagliflozin + linagliptin combination had superior efficacy and similar safety in achieving euglycaemia compared with either monotherapy. This combination, administered once daily, has the potential to reduce regimen complexity, enhance adherence and improve outcomes in clinical practice.     

β (CCL2) and α (CXCL10) chemokine modulations by cytokines and peroxisome proliferator-activated receptor-α agonists in Graves' ophthalmopathy

No data are present in the literature about the effect of cytokines on the prototype β chemokine (C-C motif) ligand 2 (CCL2) or of peroxisome proliferator-activated receptor α (PPARα (PPARA)) activation on CCL2 and CXCL10 chemokines secretion in fibroblasts or preadipocytes in Graves' ophthalmopathy (GO). We have tested the effect of interferon γ (IFNγ (IFNG)) and tumor necrosis factor α (TNFα) on CCL2, and for comparison on the prototype α chemokine (C-X-C motif) ligand 10 (CXCL10), and the possible modulatory role of PPARα activation on secretion of these chemokines in normal and GO fibroblasts or preadipocytes in primary cell cultures. This study shows that IFNγ alone, or in combination with TNFα, stimulates the secretion of CCL2 in primary orbital fibroblasts or preadipocytes from patients with GO at levels similar to those observed in controls. IFNγ and TNFα also stimulated CXCL10 chemokine secretion as expected. The presence of PPARα and PPARγ (PPARG) in primary fibroblasts or preadipocytes of patients with GO has been confirmed. PPARα activators were able to inhibit the secretion of CXCL10 and CCL2, while PPARγ activators were confirmed to be able to inhibit CXCL10 but had no effect on CCL2. PPARα activators were stronger inhibitors of chemokine secretions than PPARγ agonists. In conclusion, CCL2 and CXCL10 are modulated by IFNγ and TNFα in GO. PPARα activators inhibit the secretion of the main prototype α (CXCL10) and β (CCL2) chemokines in GO fibroblasts or preadipocytes, suggesting that PPARα may be involved in the modulation of the immune response in GO.     

Mechanisms for the antihyperglycemic effect of sitagliptin in patients with type 2 diabetes

Context: Dipeptidyl peptidase IV (DPP-4) inhibitors improve glycemic control in patients with type 2 diabetes. The underlying mechanisms (incretin effect, β-cell function, endogenous glucose production) are not well known. Objective: The aim of the study was to examine mechanisms of the antihyperglycemic effect of DPP-4 inhibitors. Design, Setting, and Patients: We administered a mixed meal with glucose tracers ([6,6-(2)H(2)]-glucose infused, [1-(2)H]-glucose ingested), and on a separate day, a glucose infusion matched the glucose responses to the meal (isoglycemic test) in 50 type 2 diabetes patients (hemoglobin A(1c) = 7.4 ± 0.8%) and seven controls; 47 diabetic completers were restudied after 6 wk. Glucose fluxes were calculated, and β-cell function was assessed by mathematical modeling. The incretin effect was calculated as the ratio of oral to iv insulin secretion. Intervention: We conducted a 6-wk, double-blind, randomized treatment with sitagliptin (100 mg/d; n = 25) or placebo (n = 22). Results: Relative to placebo, meal-induced changes in fasting glucose and glucose area under the curve (AUC) were greater with sitagliptin, in parallel with a lower appearance of oral glucose [difference (post-pre) AUC = -353 ± 915 vs. +146 ± 601 μmol · kg(-1) · 5 h] and greater suppression of endogenous glucose production. Insulin sensitivity improved 10%, whereas total insulin secretion was unchanged. During the meal, β-cell glucose sensitivity improved (+19[29] vs. 5[21] pmol · min(-1) · m(-2) · mm(-1); median [interquartile range]) and glucagon AUC decreased (19.6 ± 7.5 to 17.3 ± 7.1 ng · ml(-1) · 5 h), whereas intact glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 AUC increased with sitagliptin vs. placebo. The incretin effect was unchanged because sitagliptin increased β-cell glucose sensitivity also during the isoglycemic test. Conclusions: Chronic sitagliptin treatment improves glycemic control by lowering the appearance of oral glucose, postprandial endogenous glucose release, and glucagon response, and by improving insulin sensitivity and β-cell glucose sensing in response to both oral and iv glucose.     

Endothelial dysfunction in type 2 diabetes

The mechanisms responsible for the accelerated atherosclerosis observed in type 2 diabetes are not fully understood. One of the earliest events in the development of atherosclerosis is endothelial dysfunction, namely, a reduction in nitric oxide (NO) synthesis or its bioavailability within the peri-endothelial environment, where it is responsible for maintenance of vascular tissue integrity. The clinical evaluation of this pathway is hampered by the fact that in vivo NO cannot be directly measured; however, exploiting a novel, complex and elegant experimental setup, McVeigh and co-workers (Diabetologia 1992;35:771–776) were the first to document that NO bioavailability in type 2 diabetic patients is indeed reduced. In this edition of ‘Then and now’ that paper is reappraised not only for its originality, but also for the broad and extensive evaluation of the vascular functions explored, the complete clinical characterisation of patients enrolled and for the fact that all the major findings were subsequently replicated.     

Membranous glomerulonephritis secondary to allogeneic stem cell transplant: review of the literature

Renal injury associated with hematopoietic stem cell transplant (HSCT) may be related to a combination of factors. Chronic graft-versus-host disease (cGVHD) is the most common complication of allogeneic HSCT. Although the kidneys are not considered the primary target organs for GVHD, chronic impairment of renal function may occur in 20% to 60% of HSCT patients. Membranous glomerulonephritis (MG) is the most frequent renal complication observed in patients who develop nephrotic syndrome after allogeneic HSCT. In this setting, the pathogenesis of MG is not clearly understood and the most appropriate treatment approach has not been established. In order to summarize the current knowledge on this issue, a review of the pertinent literature has been performed. The available data on MG diagnosed in patients submitted to allogeneic HSCT were identified using the MEDLINE database (last accessed: Jan 30, 2012). Fifty-nine patients with allogeneic HSCT-related MG with a median age of 43 years were identified. MG occurred at a median time of 17 months after allogeneic HSCT. A history of acute or concomitant clinically apparent cGVHD was present in 69% and 31% of cases, respectively. cGVHD, nonmyeloablative conditioning regimens, immunosuppression withdrawal, and the use of peripheral blood stem cell grafts were identified as risk factors. Among the 53 patients with available outcome data, complete remission, partial response, and inefficacy of treatment were recorded in 65%, 22% and 13% of cases, respectively. MG after allogeneic HSCT seems to be etiologically related to subclinical or overt cGVHD, which flares up after discontinuation of immunosuppression. The available measures can induce sustained long-term remission in about two-thirds of affected patients.