Cardiovascular risk in type 2 diabetics and pharmacological regulation of mealtime glucose excursions

RING finger protein 10 is a potential drug target for diabetic vascular complications

Vascular remodeling induced by long-term hyperglycaemia is the main pathological process in diabetic vascular complications. Thus, vascular remodeling may be a potential therapeutic target in diabetes mellitus (DM) with macrovascular disease. The present study aimed to investigate the effect of RING finger protein 10 (RNF10) on vascular remodeling under conditions of chronic hyperglycaemia stimulation. We found that overexpression of RNF10 clearly decreased intimal thickness and attenuated vascular remodeling in DM. TUNEL staining showed that apoptosis was clearly inhibited, an effect that may be mediated by decreases in Bcl-2 protein expression. Quantitative analysis demonstrated that overexpression of RNF10 could suppress inflammation by reducing the levels of TNF-α, and MCP-1 mRNA and NF-κB protein. Meanwhile, overexpression of RNF10 prevented vascular smooth muscle cell (VSMC) hyperproliferation through the downregulation of cyclin D1 and CDK4 proteins. Notably, short hairpin RNF10 (shRNF10) greatly aggravated the pathological responses of diabetic vascular remodeling. These outcomes revealed that the differential expression of RNF10 had a completely opposite effect on vascular damage under hyperglycaemia, further displaying the core function of RNF10 in regulating vascular remodeling induced by diabetes. Consequently, RNF10 could be a novel target for the treatment of diabetic vascular complications.

Impact of glucose-lowering therapies on risk of stroke in type 2 diabetes

Patients with type 2 diabetes (T2D) have an increased risk of stroke compared with people without diabetes. However, the effects of glucose-lowering drugs on risk of ischaemic stroke in T2D have been less extensively investigated than in coronary heart disease. Some evidence, including the UKPDS, has suggested a reduced risk of stroke with metformin, although the number of studies is limited. Inhibition of the K_ATP channels increases ischaemic brain lesions in animals. This is in agreement with a recent meta-analysis showing an increased risk of stroke with sulphonylureas vs. various comparators as both mono- and combination therapy. Pioglitazone can prevent recurrence of stroke in patients with previous stroke, as already shown in PROactive, although results are less clear for first strokes. As for DPP-4 inhibitors, there was a non-significant trend towards benefit for stroke, whereas a possible increased risk of stroke with SGLT2 inhibitors-and in particular, empagliflozin in the EMPA-REG OUTCOME trial-has been suggested and requires clarification. Experimental results support a potential protective effect of GLP-1 receptor agonists against stroke that has, at least in part, been translated to clinical benefits in T2D patients in the LEADER and SUSTAIN-6 trials. Further interventional studies are now warranted to confirm the effects of glucose-lowering agents on risk of stroke in patients with T2D. In summary, the effects of antidiabetic drugs on risk of stroke appear to be heterogeneous, with some therapies (pioglitazone, GLP-1 receptor agonists) conferring possible protection against ischaemic stroke, other classes showing a neutral impact (DPP-4 inhibitors, insulin) and some glucose-lowering agents being associated with an increased risk of stroke (sulphonylureas, possibly SGLT2 inhibitors, high-dose insulin in the presence of insulin resistance).

Investigation on cardiovascular risk prediction using physiological parameters

Cardiovascular disease (CVD) is the leading cause of death worldwide. Early prediction of CVD is urgently important for timely prevention and treatment. Incorporation or modification of new risk factors that have an additional independent prognostic value of existing prediction models is widely used for improving the performance of the prediction models. This paper is to investigate the physiological parameters that are used as risk factors for the prediction of cardiovascular events, as well as summarizing the current status on the medical devices for physiological tests and discuss the potential implications for promoting CVD prevention and treatment in the future. The results show that measures extracted from blood pressure, electrocardiogram, arterial stiffness, ankle-brachial blood pressure index (ABI), and blood glucose carry valuable information for the prediction of both long-term and near-term cardiovascular risk. However, the predictive values should be further validated by more comprehensive measures. Meanwhile, advancing unobtrusive technologies and wireless communication technologies allow on-site detection of the physiological information remotely in an out-of-hospital setting in real-time. In addition with computer modeling technologies and information fusion. It may allow for personalized, quantitative, and real-time assessment of sudden CVD events.

Pentoxifylline aggravates fatty liver in obese and diabetic ob/ob mice by increasing intestinal glucose absorption and activating hepatic lipogenesis

BACKGROUND AND PURPOSE

Pentoxifylline is in clinical trials for non-alcoholic fatty liver disease and diabetic nephropathy. Metabolic and hepatic effects of pentoxifylline were assessed in a murine model of obesity and type 2 diabetes.

EXPERIMENTAL APPROACH

Pentoxifylline (100 mg·kg(-1) ·day(-1)) was administered for 4 days or 3 weeks in lean and obese/diabetic ob/ob mice. Plasma lipids, glucose, other metabolites and relevant enzymes were measured by standard assays. Hepatic lipids in vivo were assessed with magnetic resonance spectroscopy and by histology. Hepatic extracts were also analysed with RT-PCR and Western blotting.

KEY RESULTS

Four days of pentoxifylline treatment slightly increased liver lipids in ob/ob mice. After 3 weeks, pentoxifylline exacerbated fatty liver and plasma transaminases in ob/ob mice but did not induce liver steatosis in lean mice. Plasma glucose was highest in fed, but not fasted, ob/ob mice treated with pentoxifylline. During the first 10 min of an oral glucose tolerance test, blood glucose increased more rapidly in pentoxifylline-treated mice. Jejunal expression of glucose transporter 2 isoform was increased in pentoxifylline-treated obese mice. Hepatic activity of carbohydrate response element binding protein (ChREBP) increased after pentoxifylline in ob/ob, but not lean, mice. Hepatic expression of lipogenic enzymes was highest in pentoxifylline-treated ob/ob mice. However, pentoxifylline reduced markers of oxidative stress and inflammation in ob/ob liver.

CONCLUSION AND IMPLICATIONS

Pentoxifylline exacerbated fatty liver in ob/ob mice through enhanced intestinal glucose absorption, increased postprandial glycaemia and activation of hepatic lipogenesis. Long-term treatment with pentoxifylline could worsen fatty liver in some patients with pre-existing hyperglycaemia.

Metabolic effect of repaglinide or acarbose when added to a double oral antidiabetic treatment with sulphonylureas and metformin: a double-blind, cross-over, clinical trial

OBJECTIVE

To compare the metabolic effects of acarbose and repaglinide in type 2 diabetic patients who are being treated with a sulphonylurea-metformin combination therapy. The primary endpoint of the study was to evaluate which add-on treatment between acarbose and repaglinide is more efficacious in reducing PPG. The second endpoint was to evaluate which of these two treatment is more efficacious in the global management of glucose homeostasis in the enrolled patients.

RESEARCH DESIGN AND METHODS

After a 4-week run-in period with a sulphonylurea-metformin combination, 103 patients were randomised to receive in addition either repaglinide, up to 6 mg/day (2 mg three times a day) or acarbose, up to 300 mg/day (100 mg three times a day) with forced titration (independently of their glycaemic control, unless side-effects developed due to the drug dosage) for 15 weeks. The treatment was then crossed-over for further 12 weeks until the 27th week. We assessed body mass index (BMI), glycosylated haemoglobin (HbA(1c)), fasting plasma glucose (FPG), postprandial plasma glucose (PPG), fasting plasma insulin (FPI), postprandial plasma insulin (PPI), homeostatic model assessment (HOMA) index, systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides (Tg), at baseline and at 1, 2, 15 and 27 weeks of treatment.

RESULTS

Seven patients did not complete the study, comprising one patient who was lost to follow-up and a further six through side-effects (two in week 1, one in week 15 and three after cross-over) Side-effects were classified as nausea (one in acarbose group), gastrointestinal events (four in acarbose group), and hypoglycaemia (one in repaglinide group). After 15 weeks of therapy, the repaglinide-treated patients experienced a significant decrease in HbA(1c) (-1.1%, p < 0.05), FPG (-9.5%, p < 0.05), and PPG (-14.9%, p < 0.05), when compared to the baseline values. However, the same treatment was associated with a significant increase in body weight (+2.3%, p < 0.05), BMI (+3.3%, p < 0.05) and FPI (+22.5%, p < 0.05); The increase was reversed during the cross-over phase. After 15 weeks of therapy, the acarbose-treated patients experienced a significant decrease in body weight (-1.9%, p < 0.05), BMI (-4.1%, p < 0.05), HbA(1c) (-1.4%, p < 0.05), FPG (-10.7%, p < 0.05), PPG (-16.2%, p < 0.05), FPI (-16.1%, p < 0.05), PPI (-26.9%, p < 0.05), HOMA index (-30.1%, p < 0.05), when compared to the baseline values. All these changes were reversed during the cross-over study phase, except those relating to HbA(1c), FPG and PPG. The only changes that significantly differed when directly comparing acarbose- and repaglinide-treated patients were those relating to FPI (-16.1% vs. +22.5%, respectively, p < 0.05) and HOMA index (-30.1% vs. +2.7%, p < 0.05).

CONCLUSION

In addition from having a similar effect to repaglinide on PPG, acarbose appeared to have a more comprehensive positive effect on glucose metabolism compared to repaglinide in this relatively small sample of type 2 diabetic patients when used as add-on therapy to sulphonylureas and metformin.

Impact of therapeutic advances on hypoglycaemia in type 2 diabetes

Patients with type 2 diabetes experience hypoglycaemia less frequently than those with type 1 diabetes. Some protection against hypoglycaemia is afforded by the relatively intact glucose counter-regulatory pathways that characterize the pathophysiology of early type 2 diabetes. To some extent, this protection explains why hypoglycaemic episodes in intensively treated individuals with type 2 diabetes, when they occur, are rarely severe. As diabetes progresses and therapy intensifies to achieve recommended glycaemic goals, hypoglycaemia frequency and severity increase. Thus, when it comes to instituting intensive therapy, fear of hypoglycaemia may contribute to health-care providers' 'clinical inertia'. Because maintaining glycaemic control is so important to both public and individual health, many new therapies and technologies have been developed. This manuscript reviews and considers whether these advancements in therapy make glycaemic goals easier to achieve by minimizing hypoglycaemia. Putting the hypoglycaemia experienced by type 2 diabetes patients into appropriate clinical perspective, the impact of recent progress made in pharmacotherapy, drug delivery systems, and BG monitoring on hypoglycaemia incidence is largely positive. The extent to which this progress can effect improvement over traditional therapies will, however, depend upon patient (and provider) education, motivation and behaviour change.

Combination of chromium and biotin improves coronary risk factors in hypercholesterolemic type 2 diabetes mellitus: a placebo-controlled, double-blind randomized clinical trial

Dyslipidemia, often found in type 2 diabetes mellitus (T2DM) patients, plays an important role in the progression of cardiometabolic syndrome. Two essential nutrients, chromium and biotin, may maintain optimal glycemic control. The authors report here a randomized, double-blind placebo-controlled trial (N=348; chromium picolinate and biotin combination [CPB]: 226, placebo: 122; T2DM participants with hemoglobin A1c [HbA1c] >or=7%) evaluating the effects of CPB on lipid and lipoprotein levels. Participants were randomly assigned (2:1 ratio) to receive either CPB (600 microg chromium as chromium picolinate and 2 mg biotin) or a matching placebo once daily for 90 days. Statistical analyses were conducted in all eligible participants. Subsequent supplemental analyses were performed in T2DM participants with hypercholesterolemia (HC) and in those using stable doses of statins. In the primary analysis, CPB lowered HbA1c (P<.05) and glucose (P<.02) significantly compared with the placebo group. No significant changes were observed in other lipid levels. In participants with HC and T2DM, significant changes in total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels and atherogenic index were observed in the CPB group (P<.05). Significant decreases in LDL-C, total cholesterol, HbA1c , and very low-density cholesterol levels (P<.05) were observed in the CPB group taking statins. CPB treatment was well tolerated with no adverse effects, dissimilar from those associated with placebo. These data suggest that intervention with CPB improves cardiometabolic risk factors.

Biomedical imaging research opportunities workshop IV: a white paper

The Fourth Biomedical Imaging Research Opportunities Workshop (BIROW IV) was held on February 24-25, 2006, in North Bethesda, MD. The workshop focused on opportunities for research and development in four areas of imaging: imaging of rodent models; imaging in drug development; imaging of chronic metabolic disease: diabetes; and image guided intervention in the fourth dimension-time. These topics were examined by four keynote speakers in plenary sessions and then discussed in breakout sessions devoted to identifying research opportunities and challenges in the individual topics. This paper synthesizes these discussions into a strategy for future research directions in biomedical imaging.

Predicting more accurately the overall glucose response to a lunch meal by using the postprandial glucose peak

Although the assessment of postprandial glycemia is clinically important, the most relevant time points with the smallest number of blood samples giving the highest predictive power have yet to be established. It has been suggested that a sample estimating the postprandial peak concentration would improve this predictive power compared to the usual recommended time points. In this study, we assessed the power of these time points to predict the glucose response to a meal mimicking everyday life. Subjects were 11 healthy young men (mean age, 22 +/- 1 years; body mass index, 21.7 +/- 1.8 kg/m(2)). Plasma glucose, insulin, and nonesterified fatty acids were measured by continuous collection of blood in tubes filled every 5 minutes for 240 minutes after a 2-item lunch meal consumed ad libitum on the first test day, and in the same amount 1 week later. The most relevant time point for the plasma glucose peak level was found at 45 minutes (mean interval, 47 +/- 3 minutes) and was not dependent on the energy intake at lunch. Its coefficient of variation was low (7.0% +/- 1.5%). The best predictive equation for the whole postmeal glucose area under the curve (AUC) was found at 120 minutes and involved glucose, insulin, and nonesterified fatty acids (r(2) = 0.89; P < 10(-7)). The 120-minute postmeal glucose profile constructed with the 0-, 45-, 90-, and 120-minute time points overlapped more accurately with the actual profile than did the time points normally used in the glucose tolerance test, and slightly improved the correlation between the calculated and the actual plasma glucose area under the curve (r = 0.96; P < 10(-7)). In conclusion, in healthy, young, lean male subjects, a blood sample collected 45 minutes after a spontaneous lunch meal estimates the postprandial plasma glucose peak and suggests that including the peak level along with 90- and 120-minute time points may improve the predictive power of the plasma glucose profile after a meal.

The impact of antidiabetic therapies on cardiovascular disease

Cardiovascular disease disproportionately affects people with diabetes and is a leading cause of death. Glycemic control has so far not been conclusively shown to decrease cardiovascular events. The therapeutic agents used in treating glycemia have different effects on cardiovascular risks and, therefore, may have different effects on outcome. Insulin sensitizers impact cardiovascular risk factors, including dyslipidemia and fibrinolysis. Metformin is the only oral antidiabetic medication shown to decrease cardiovascular events independent of glycemic control. Thiazolidinediones improve insulin resistance and lower insulin concentrations, which is beneficial because hyperinsulinemia is an independent predictor of cardiovascular disease. Insulin therapy acutely reduces cardiovascular mortality and morbidity in patients with diabetes and known coronary artery disease and also in patients with hyperglycemia when critically ill, but the long-term effects are unclear. In contrast, insulin secretagogues have very little effect on both cardiovascular risk factors and outcomes.