The effect of Mediterranean diet on the development of type 2 diabetes mellitus: a meta-analysis of 10 prospective studies and 136,846 participants

OBJECTIVE

The purpose of this work was to meta-analyze prospective studies that have evaluated the effect of a Mediterranean diet on the development of type 2 diabetes.

MATERIALS/METHODS

PubMed, Embase and the Cochrane Central Register of Controlled Trials databases were searched up to 20 November 2013. English language publications were allocated; 17 original research studies (1 clinical trial, 9 prospective and 7 cross-sectional) were identified. Primary analyses were limited to prospective studies and clinical trials, yielding to a sample of 136,846 participants. A systematic review and a random effects meta-analysis were conducted.

RESULTS

Higher adherence to the Mediterranean diet was associated with 23% reduced risk of developing type 2 diabetes (combined relative risk for upper versus lowest available centile: 0.77; 95% CI: 0.66, 0.89). Subgroup analyses based on region, health status of participants and number of confounders controlling for, showed similar results. Limitations include variations in Mediterranean diet adherence assessment tools, confounders' adjustment, duration of follow up and number of events with diabetes.

CONCLUSIONS

The presented results are of major public health importance, since no consensus exists concerning the best anti-diabetic diet. Mediterranean diet could, if appropriately adjusted to reflect local food availability and individual's needs, constitute a beneficial nutritional choice for the primary prevention of diabetes.

The effects of a Mediterranean diet on the need for diabetes drugs and remission of newly diagnosed type 2 diabetes: follow-up of a randomized trial

OBJECTIVE

To assess the long-term effects of dietary interventions on glycemic control, need for diabetes medications, and remission of type 2 diabetes.

RESEARCH DESIGN AND METHODS

Originally, in a two-arm trial design, overweight, middle-aged men and women with newly diagnosed type 2 diabetes were randomized to a low-carbohydrate Mediterranean diet (LCMD; n = 108) or a low-fat diet (n = 107). After 4 years, participants who were still free of diabetes medications were further followed up until the primary end point (need of a diabetic drug); remission of diabetes (partial or complete) and changes in weight, glycemic control, and cardiovascular risk factors were also evaluated.

RESULTS

The primary end point was reached in all participants after a total follow-up of 6.1 years in the low-fat group and 8.1 years in the LCMD group; median survival time was 2.8 years (95% CI 2.4-3.2) and 4.8 years (4.3-5.2), respectively. The unadjusted hazard ratio for the overall follow-up was 0.68 (0.50-0.89; P < 0.001). LCMD participants were more likely to experience any remission (partial or complete), with a prevalence of 14.7% (13.0-16.5%) during the first year and 5.0% (4.4-5.6%) during year 6 compared with 4.1% (3.1-5.0%) at year 1 and 0% at year 6 in the low-fat diet group.

CONCLUSIONS

In patients with newly diagnosed type 2 diabetes, an LCMD resulted in a greater reduction of HbA1c levels, higher rate of diabetes remission, and delayed need for diabetes medication compared with a low-fat diet.

Simultaneous GLP-1 and insulin administration acutely enhances their vasodilatory, antiinflammatory, and antioxidant action in type 2 diabetes

OBJECTIVE

To test the hypothesis that the simultaneous administration of GLP-1 and insulin may increase their vasodilatory, antiinflammatory, and antioxidant action in type 2 diabetes.

RESEARCH DESIGN AND METHODS

In two groups of persons with type 2 diabetes, two sets of experiments were performed. The first group had two normoglycemic-normoinsulinemic clamps with or without GLP-1 and two normoglycemic-hyperinsulinemic clamps with or without GLP-1. The second group had two hyperglycemic-normoinsulinemic clamps and two hyperglycemic-hyperinsulinemic clamps with or without GLP-1.

RESULTS

During the normoglycemic-hyperinsulinemic clamp, flow-mediated dilatation (FMD) increased, while soluble intercellular adhesion molecule (sICAM-1), plasma 8-iso-prostaglandin F2α (8-iso-PGF2α), nitrotyrosine, and interleukin (IL)-6 decreased compared with normoglycemic-normoinsulinemic clamp. Similar results were obtained with the infusion of GLP-1 during the normoglycemic-normoinsulinemic clamp. The combination of hyperinsulinemia and GLP-1 in normoglycemia was accompanied by a further FMD increase and sICAM-1, 8-iso-PGF2α, nitrotyrosine, and IL-6 decrease. During the hyperglycemic-normoinsulinemic clamp, FMD significantly decreased, while sICAM-1, 8-iso-PGF2α, nitrotyrosine, and IL-6 significantly increased. When hyperglycemia was accompanied by hyperinsulinemia or by the simultaneous infusion of GLP-1, these phenomena were attenuated. The simultaneous presence of hyperinsulinemia and GLP-1 had an increased beneficial effect.

CONCLUSIONS

Our results show that the combination of insulin and GLP-1 is more effective than insulin or GLP-1 alone in improving endothelial dysfunction, inflammation, and oxidative stress in type 2 diabetes.

Personalized therapy algorithms for type 2 diabetes: a phenotype-based approach

Type 2 diabetes is a progressive disease with a complex and multifactorial pathophysiology. Patients with type 2 diabetes show a variety of clinical features, including different “phenotypes” of hyperglycemia (eg, fasting/preprandial or postprandial). Thus, the best treatment choice is sometimes difficult to make, and treatment initiation or optimization is postponed. This situation may explain why, despite the existing complex therapeutic armamentarium and guidelines for the treatment of type 2 diabetes, a significant proportion of patients do not have good metabolic control and at risk of developing the late complications of diabetes. The Italian Association of Medical Diabetologists has developed an innovative personalized algorithm for the treatment of type 2 diabetes, which is available online. According to the main features shown by the patient, six algorithms are proposed, according to glycated hemoglobin (HbA_1c, ≥9% or ≤9%), body mass index (≤30 kg/m² or ≥30 kg/m²), occupational risk potentially related to hypoglycemia, chronic renal failure, and frail elderly status. Through self-monitoring of blood glucose, patients are phenotyped according to the occurrence of fasting/preprandial or postprandial hyperglycemia. In each of these six algorithms, the gradual choice of treatment is related to the identified phenotype. With one exception, these algorithms contain a stepwise approach for patients with type 2 diabetes who are metformin-intolerant. The glycemic targets (HbA_1c, fasting/preprandial and postprandial glycemia) are also personalized. This accessible and easy to use algorithm may help physicians to choose a personalized treatment plan for each patient and to optimize it in a timely manner, thereby lessening clinical inertia.

Glycaemic durability with dipeptidyl peptidase-4 inhibitors in type 2 diabetes: a systematic review and meta-analysis of long-term randomised controlled trials

OBJECTIVES

To evaluate glycaemic durability with dipeptidyl peptidase-4 (DPP-4) inhibitors in type 2 diabetes.

DESIGN

A systematic review and meta-analysis of long-term randomised trials of DPP-4 inhibitors on haemoglobin A1c (HbA1c) was conducted. Electronic searches were carried out on the following databases: MEDLINE, EMBASE, Scopus and Web of Knowledge to December 2013. Searches were supplemented by a review of trial registries and references from identified trials. Trials were included if they lasted at least 76 weeks, and had intermediate and final assessments of HbA1c. Citations and full-text articles were screened by two reviewers. A random effect model was used to pool data.

PARTICIPANTS

Adults with type 2 diabetes.

INTERVENTIONS

Any DPP-4 inhibitor (sitagliptin, vildagliptin, saxagliptin, linagliptin and alogliptin).

OUTCOME MEASURES

The difference between final and intermediate HbA1c assessment was the primary outcome.

RESULTS

We screened 461 citations and reviewed 12 articles reporting 12 trials in 14 829 participants. All trials were of 76 weeks duration at least. The difference in HbA1c changes between final and intermediate points averaged 0.22% (95% CI 0.15% to 0.29%), with high heterogeneity (I(2)=91%, p<0.0001). Estimates of differences were not affected by the analysis of six extension trials (0.24%, 0.02 to 0.46), or five trials in which a DPP-4 inhibitor was added to metformin (0.24%, 0.16 to 0.32).

CONCLUSIONS

There is evidence that the effect of DPP-4 inhibitors on HbA1c in type 2 diabetes significantly declines during the second year of treatment. Future research should focus on the characteristics of patients that benefit most from DPP-4 inhibitors in terms of glycaemic durability.

Unhealthy diets: a common soil for the association of metabolic syndrome and cancer

The association between metabolic syndrome and cancer continues to be acknowledged. Metabolic syndrome is a common long-term complication in cancer survivors; on the other hand, findings from several recent meta-analyses suggest that the presence of metabolic syndrome is associated with increased risk of future cancer at specific sites. Approximately one-third of cancer deaths occurring in the USA each year may be caused by unhealthy lifestyle habits, including poor nutrition. Worldwide, diets low in fruits rank third for deaths attributable to individual risk factors. Metabolic syndrome may be a surrogate marker for dietary risk factors for cancer, a sentinel for the deleterious effect of unhealthy diet in susceptible individuals, who may first manifest metabolic consequences (visceral obesity, dysglycemia, hypertension, and dyslipidemia), and then an increased risk of cancer. From the standpoint of preventive oncology, people with the metabolic syndrome should be encouraged, more than sex- and age-matched counterparts, to undergo appropriate cancer screenings.

Baseline glycemic parameters predict the hemoglobin A1c response to DPP-4 inhibitors : meta-regression analysis of 78 randomized controlled trials with 20,053 patients

Ability to predict which patients might benefit more of therapy might facilitate personalization of treatment. The aim of this study was to obtain information about clinical characteristics which might predict the HbA1c response to DPP-4 inhibitors. We conducted an electronic search without restriction for randomized controlled trials (RCTs) involving DPP-4 inhibitors (vildagliptin, sitagliptin, saxagliptin, linagliptin, and alogliptin). RCTs were included if they lasted at least 12 weeks, reported the effect of DPP-4 inhibitors on HbA1c level, and the number of patients in any arm was >30. We did a meta-regression analysis. Seventy-eight articles were eligible, with 79 arms and 20,503 patients. For all arms, the decrease of HbA1c was -0.74 % (95 % CI -0.80 to -0.67 %), with considerable heterogeneity (I (2) = 97 %, P < 0.0001): the greatest HbA1c decrease was seen at 52 weeks (8 arms, 3,338 patients, -0.88 %, 95 % CI -1.10 to -0.66 %). In univariate meta-regression analysis, baseline HbA1c explained 22 % of variance of the HbA1c response to treatment, while fasting glucose and type of DPP-4 inhibitor explained an additional 19 and 12 %, respectively; age, duration of treatment, previous therapy, and type of statistical analysis of RCTs were without influence. In the multivariate meta-regression model, baseline HbA1c, fasting glucose, and type of DPP-4 inhibitor explained 61 % of total variance. The HbA1c response to DPP-4 inhibitors can be modulated mainly by baseline HbA1c and fasting glucose levels: a greater absolute reduction of baseline HbA1c is seen in patients with higher baseline HbA1c and lower fasting glucose level.

A nomogram to estimate the proportion of patients at hemoglobin A1c target <7% with noninsulin antidiabetic drugs in type 2 diabetes: a systematic review of 137 randomized controlled trials with 39,845 patients

We assessed the efficacy of noninsulin antidiabetic medications used in current clinical practice (metformin, sulfonylureas, α-glucosidase inhibitors, thiazolidinediones, glinides, dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 agonists) to reach the HbA1c target <7% in people with type 2 diabetes. MEDLINE, EMBASE, and the Cochrane CENTRAL were searched from inception through April 2011 for randomized controlled trials (RCTs) involving noninsulin antidiabetic drugs. RCTs had to report the effect of any diabetes medication on the HbA1c levels, to include at least 30 subjects in every arm of the study, and to last at least 12 weeks. Data were summarized across studies using random-effects meta-regression. We found 137 RCTs with 205 arms and 39,845 patients. The proportion of patients who achieved the HbA1c goal ranged from 25.9% (95% CI 18.5-34.9) with α-glucosidase inhibitors to 48.6% (95% CI, 53.6) with GLP-1 analogs. Baseline HbA1c was the major determinant of the proportion of patients at HbA1c goal. The meta-regression model with mean baseline HbA1c value, concomitant drug use, and class of drugs as covariates explained almost 67% of the between-study variability. A nomogram was developed to estimate the proportion of patients at target for each noninsulin drug class: for a baseline HbA1c level of 7.5%, all noninsulin drugs, except α-glucosidase inhibitors, achieved the HbA1c goal <7% in more than 50% of patients. Starting or intensifying pharmacological therapy at baseline HbA1c 8% or less was associated with more than 50% of patients at HbA1c goal for most noninsulin drugs.

Metabolic syndrome and cancer: holistic or reductionist?

Metabolic syndrome has become a major public health problem worldwide and represents a common clinical condition in countries with a high incidence of obesity and western dietary patterns. Metabolic syndrome associates with common cancers at many sites, including liver, colorectal, and bladder cancers in men, and endometrial, pancreatic, breast post-menopausal, and colorectal cancers in women. However, the role played by each single component of the syndrome on cancer risk is still unclear. For endometrial cancer, obesity and/or high circumference waist explain all the risk associated with the full metabolic syndrome, while for post-menopausal breast cancer, the risk conveyed by metabolic syndrome appears to be greater than its parts, as no single component explains the full risk associated with the syndrome. Future research should cover other avenues in order to elucidate the complexity of biological processes linking metabolic syndrome and cancer.

Cardiovascular guidelines: separate career may help attenuate controversy

The release of recent guidelines for high cholesterol, hypertension and diabetes in the U.S. has been accompanied by great noise and concerns, both in the academic circuits and the lay press. For persons aged 40 to 75 years, with LDL cholesterol levels between 70-189 mg/dL and 7.5% or higher estimated 10-year risk, the peril of a global "statinization" has been advocated, predicting a 70% increase of statin use in this otherwise healthy people. A minority of the Eight Joint National Committee panel disagreed with the recommendation to increase the target systolic blood pressure from 140 to 150 mmHg in persons aged 60 years or older without diabetes mellitus or chronic kidney disease. The 2013-American Association of Clinical Endocrinologists algorithm and consensus statement on diabetes has been criticized with particular concerns about transparency, conflicts of interest, group composition, and the abundant use of personal judgment and experience instead of rigorous methodology. Separate careers for experts who collect evidence from persons who write the actual guidelines seems a good opportunity in order to attenuate the noise associated with release of new guidelines, especially those that counter prior practice.

The development of new basal insulins: is there any clinical advantage with their use in type 2 diabetes?

INTRODUCTION

The basal insulin products currently on market do not optimally mimic endogenous insulin secretion. These unmet clinical needs have fueled the development of new basal insulin analogues for improving their pharmacokinetics/pharmacodynamics profile.

AREAS COVERED

We review the recent literature investigating the efficacy and safety of new basal insulin analogues in type 2 diabetes, as in the USA, insulin utilization accounted for 26% of treatment visits for these patients in 2012. Insulin degludec is a desB30 insulin acylated at the LysB29 residue with a glutamate linker and 16-carbon fatty diacyl side chain. Insulin lispro has been PEGylated at lysine B28, via a urethane bond, which increases the hydrodynamic size of the molecule and reduces its absorption and clearance following subcutaneous administration. Glargine U300 represents a new high-strength glargine formulation (300 U/ml): once injected, U300 forms a compact subcutaneous depot with a smaller surface area to produce a more gradual and prolonged release. Both PEG-lispro and glargine U300 are not yet on the market.

EXPERT OPINION

Ultra-long acting and high-strength formulations of new basal analogues have the potential for less glycemic variability, less (nocturnal) hypoglycemia and weight-loss advantage for PEG-lispro. However, these new basal insulin analogues need to be monitored closely for adverse signals.

Mediterranean diet and type 2 diabetes

Consumption of selected dietary components is favourably associated with prevention of type 2 diabetes, but discordant results for some foods or single nutrients continue to appear. The study of complete dietary patterns represents the most adequate approach to assess the role of diet on the risk of diabetes. The term 'Mediterranean diet' essentially refers to a primarily plant-based dietary pattern whose greater consumption has been associated with higher survival for lower all-cause mortality. At least five large prospective studies report a substantially lower risk of type 2 diabetes in healthy people or at risk patients with the highest adherence to a Mediterranean diet. Five randomized controlled trials have evaluated the effects of a Mediterranean diet, as compared with other commonly used diets, on glycaemic control in subjects with type 2 diabetes. Improvement of HbA1c levels was greater with a Mediterranean diet and ranged from 0.1% to 0.6% for HbA1c . No trial reported worsening of glycaemic control with a Mediterranean diet. Although no controlled trial specifically assessed the role of a Mediterranean diet in reducing cardiovascular events in type 2 diabetes, there is evidence that post-infarct or high-risk patients, including diabetic patients, may have cardiovascular benefits from a Mediterranean diet. The evidence so far accumulated suggests that adopting a Mediterranean diet may help prevent type 2 diabetes; moreover, a lower carbohydrate, Mediterranean-style diet seems good for HbA1c reduction in persons with established diabetes.

Metabolic syndrome and endometrial cancer: a meta-analysis

We performed a systematic review and meta-analysis on the association of metabolic syndrome with endometrial cancer. A systematic literature search of electronic databases (Medline, ISI Web of Knowledge and Scopus) was conducted and complemented by cross-referencing to identify studies published before 31 January 2013. Core items of identified studies were independently extracted by two reviewers, and results were summarized by random effects meta-analysis. We identified six studies, which reported on 3,132 cancer cases. Metabolic syndrome was associated with an increased risk of endometrial cancer (RR: 1.89, 95 % CI 1.34-2.67, P < 0.001), with significant heterogeneity among studies (I (2) = 92 %, P < 0.001), but no indication for publication bias in the Egger's test (P = 0.240). A sensitivity analysis omitting two studies produced no heterogeneity (I (2) = 0 %) and attenuated the association (RR: 1.39, 1.31-1.48, P < 0.001). The risk estimates for any single factor of the syndrome were 2.21 (P < 0.001) for higher values of body mass index and/or waist, 1.81 (P = 0.044) for hyperglycemia, 1.81 (P = 0.024) for higher blood pressure values, and 1.17 (P < 0.001) for high triglyceride levels; there was no significant association with low HDL-cholesterol. Metabolic syndrome is associated with an increased risk of endometrial cancer; among the components of the syndrome, obesity/high waist is that more strongly associated with endometrial cancer.

Opposite influence of light and blindness on pituitary-gonadal function

Some environmental factors may influence the pituitary-gonadal function. Among these, light plays an important role in animals and in humans. The effect of light on the endocrine system is mediated by the pineal gland, through the modulation of melatonin secretion. In fact, melatonin secretion is stimulated by darkness and suppressed by light, thus its circadian rhythm peaks at night. Light plays a favorable action on the hypothalamic-pituitary axis likely inhibiting melatonin secretion, while the exogenous melatonin administration does not seem to impair the hormonal secretions of this axis. The basal and rhythmic pituitary-gonadal hormone secretions are regulated by a central clock gene and some independent clock genes in the peripheral tissues. Light is able to induce the expression of some of these genes, thus playing an important role in regulating the hormonal secretions of pituitary-gonadal axis and the sexual and reproductive function in animals and humans. The lack of light stimulus in blind subjects induces increase in plasma melatonin concentrations with a free-running rhythm of secretion, which impairs the hormonal secretions of pituitary-gonadal axis, causing disorders of reproductive processes in both sexes.

Diabetes and sexual dysfunction: current perspectives

Diabetes mellitus is one of the most common chronic diseases in nearly all countries. It has been associated with sexual dysfunction, both in males and in females. Diabetes is an established risk factor for sexual dysfunction in men, as a threefold increased risk of erectile dysfunction was documented in diabetic men, as compared with nondiabetic men. Among women, evidence regarding the association between diabetes and sexual dysfunction are less conclusive, although most studies have reported a higher prevalence of female sexual dysfunction in diabetic women as compared with nondiabetic women. Female sexual function appears to be more related to social and psychological components than to the physiological consequence of diabetes. Hyperglycemia, which is a main determinant of vascular and microvascular diabetic complications, may participate in the pathogenetic mechanisms of sexual dysfunction in diabetes. Moreover, diabetic people may present several clinical conditions, including hypertension, overweight and obesity, metabolic syndrome, cigarette smoking, and atherogenic dyslipidemia, which are themselves risk factors for sexual dysfunction, both in men and in women. The adoption of healthy lifestyles may reduce insulin resistance, endothelial dysfunction, and oxidative stress - all of which are desirable achievements in diabetic patients. Improved well-being may further contribute to reduce and prevent sexual dysfunction in both sexes.

Colorectal cancer association with metabolic syndrome and its components: a systematic review with meta-analysis

We performed a systematic review and meta-analysis of the empirical evidence on the association of metabolic syndrome and its components with colorectal cancer incidence and mortality. A systematic literature search of multiple electronic databases was conducted and complemented by cross-referencing to identify studies published before 31 October 2012. Every included study was to report risk estimates with 95 % confidence intervals for the association between metabolic syndrome and colorectal cancer (incidence or mortality). Core items of identified studies were independently extracted by two reviewers, and results were summarized by standard methods of meta-analysis. We identified 17 studies, which reported on 49 data sets with 11,462 cancer cases. Metabolic syndrome was associated with an increased risk of colorectal cancer incidence and mortality in both men (RR: 1.33, 95 % CI 1.18-1.50, and 1.36, 1.25-1.48, respectively) and women (RR: 1.41, 1.18-1.70, and 1.16, 1.03-1.30, respectively). The risk estimates changed little depending on type of study (cohort vs non cohort), populations (US, Europe, Asia), cancer site (colon and rectum), or definition of the syndrome. The risk estimates for any single factor of the syndrome were significant for higher values of BMI/waist (RR: 1.19, 95 % CI 1.10-1.28), dysglycemia (RR: 1.29, 1.11-1.49), and higher blood pressure (RR: 1.09, 1.01-1.18). Dysglycemia and/or higher BMI/waist explained most of the risk associated with metabolic syndrome. Metabolic syndrome is associated with an increased risk of colorectal cancer incidence and mortality in both sexes. The risk conveyed by the full syndrome is not superior to the sum of its parts.

Circulating endothelial progenitor cells in acromegaly

BACKGROUND

Endothelial progenitor cells (EPCs), involved in the repairing mechanisms of vascular damage, are positively correlated to insulin-like growth factor I (IGF-I) concentrations in healthy adults. However, the levels of EPCs and their role in acromegalic patients have never been investigated.

AIM

We conducted a cross-sectional study in order to assess the levels of the different phenotypes of circulating EPC in acromegalic patients.

SUBJECTS AND METHODS

The study was performed at the Endocrinology Unit of Federico II University and at the Unit of Metabolic Diseases and Endocrinology of the Second University of Naples. Fifty-five acromegalic patients and 65 healthy controls were studied. EPCs were assessed by flow cytometry and IGF-I by immunoradiometric assay.

RESULTS

Compared with subjects of the control group, acromegalic patients showed significantly higher levels of EPCs phenotypes expressing KDR antigen [KDR+, cells per 106 events, median and interquartile range, 44 (28-67) vs 23 (13-40), p=0.006; CD34+KDR+ 25 (18-38) vs 12 (8-17), p<0.001; CD133+KDR+ 17 (13-30) vs 8 (6-12), p<0.001; CD34+KDR+CD133+ 16 (12-25) vs 8 (6-10), p<0.001]. There was a positive correlations between CD34+KDR+CD133+ cells count and IGF-I in acromegaly group (r=0.79, p<0.001).

CONCLUSIONS

Acromegalic patients show higher circulating EPCs levels expressing KDR, positively correlated with IGF-I, suggesting a role for IGF-I in regulating the expression of this surface marker in the early phase of EPCs differentiation.

Does personalized diabetology overcome clinical uncertainty and therapeutic inertia in type 2 diabetes?

Uncertainties abound in clinical management of type 2 diabetes. Sources of uncertainty specific to type 2 diabetes originate from the panoply of glycemic (HbA1c) targets, the complexity of drug therapy, the ideal sequence of drugs after metformin failure, the possible harms of anti-hyperglycemic drugs, the outcomes of treatment (surrogate versus clinical) and the hierarchy of risk factors to treat in order to prevent the vascular complications. Ironically, multiple treatment guidelines and algorithms periodically released to improve guidance may generate confusion into clinicians. Moreover, treatment algorithms cannot be truly evidence-based because of a lack of studies comparing all available treatment combination options. Personalized therapy essentially identifies patients who could have major benefits from the therapy as compared with other patients. Personalized medicine for type 2 diabetic has the potential to improve the quality health-care practice of diabetes management, but specific research is needed.