Cancer incidence and mortality in patients with type 2 diabetes treated with human insulin: a cohort study in Shanghai

Causality between insulin use and malignant tumors of the digestive system: a two-sample mendelian randomized study

BACKGROUND

Existing cohort studies show no association between insulin use and cancers of the digestive system, while numerous meta-analyses suggest that insulin use increases the risk of digestive system tumours. This study uses two-sample Mendelian randomization (MR) to further investigate the causal relationship between the two.

METHODS

We selected single nucleotide polymorphisms (SNPs) strongly associated with insulin use as instrumental variables and used aggregated statistics on digestive system neoplasms as the outcome event. The primary method of analysis was inverse variance weighting (IVW), supplemented by weighted median, MR-Egger regression, weighted mode and simple mode methods. The reliability of the study was assessed by heterogeneity testing, pleiotropy analysis and sensitivity analysis.

RESULT

A total of 8 SNPs associated with insulin use were included as instrumental variables. Random-effects IVW analysis showed an association between insulin use and increased risk of colorectal cancer (OR = 1.1037, 95%CI = 1.0183-1.1962, P = 0.016). No statistically significant association was found between insulin use and the development of other digestive system tumours. The results were unaffected by pleiotropy and heterogeneity, and the reliability of the findings was confirmed by sensitivity analysis.

CONCLUSION

Our Mendelian randomization study suggests an association between insulin use and an increased risk of CRC, with no clear association observed for other digestive system tumours. However, further MR studies with larger sample sizes from genome-wide association study (GWAS) data are needed to verify this association.

Thiazolidinediones, alpha-glucosidase inhibitors, meglitinides, sulfonylureas, and hepatocellular carcinoma risk: A meta-analysis

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related death worldwide. Effects of second-line oral antidiabetic medications on incident HCC risk in individuals with type 2 diabetes mellitus remain unclear. This study evaluated associations between sulfonylureas, thiazolidinediones, meglitinides and alpha-glucosidase inhibitors, and incident HCC risk.

METHODS

We systematically reviewed all studies on PubMed, Embase and Web of Science databases. Studies were included if they documented: (1) exposure to oral antidiabetic medication classes; (2) HCC incidence; (3) relative risks/odds ratios (OR) for HCC incidence. Eight eligible observational studies were identified. We performed random-effects meta-analyses to calculate pooled adjusted ORs (aORs) and 95% confidence intervals (CI).

RESULTS

Thiazolidinedione use (7 studies, 280,567 participants, 19,242 HCC cases) was associated with reduced HCC risk (aOR = 0.92, 95% CI = 0.86-0.97, I² = 43%), including among Asian subjects (aOR = 0.90, 95% CI = 0.83-0.97), but not Western subjects (aOR = 0.95, 95% CI = 0.87-1.04). Alpha-glucosidase inhibitor use (3 studies, 56,791 participants, 11,069 HCC cases) was associated with increased HCC incidence (aOR = 1.08; 95% CI = 1.02-1.14, I² = 21%). Sulfonylurea use (8 studies, 281,180 participants, 19,466 HCC cases) was associated with increased HCC risk in studies including patients with established liver disease (aOR = 1.06, 95% CI = 1.02-1.11, I² = 75%). Meglitinide use (4 studies, 58,237 participants, 11,310 HCC cases) was not associated with HCC incidence (aOR = 1.19; 95% CI = 0.89-1.60, I² = 72%).

CONCLUSIONS

Thiazolidinedione use was associated with reduced HCC incidence in Asian individuals with diabetes. Alpha-glucosidase inhibitor or sulfonylurea use was associated with modestly increased HCC risk; future research should determine whether those agents should be avoided in patients with chronic liver disease.

For colorectal cancer patients with type II diabetes, could metformin improve the survival rate? A meta-analysis

OBJECTIVE

Current research is controversial about whether metformin can improve the survival rate of patients with colon cancer. Therefore, we conducted a meta-analysis to identify the association between metformin and the survival rate of colorectal cancer (CRC) patients with type II diabetes.

METHODS

We conducted a search in databases including Pubmed, EMBASE and Cochrane Library. All articles were published in the last decade, and the quality of each study was evaluated by the Newcastle-Ottawa Scale. Odds ratios (ORs) and its corresponding 95% confidence intervals (CIs) for each study were calculated and summary relative risk estimates with corresponding 95% CIs were generated using the random-effects model. Heterogeneity and publication bias were assessed.

RESULTS

Ten articles were included in this meta-analysis. The included articles were all cohort studies. In a pooled analysis of all studies, metformin using was associated with increased overall survival (OS) rate (OR, 0.54; 95% CI, 0.47 to 0.63) and cancer-specific survival (CS) rate (OR 0.59; 95% CI 0.43 to 0.82) of CRC patients with diabetes. We found that the effect of metformin is associated with geographical region through subgroup meta-analysis.

CONCLUSIONS

Metformin using was associated with an increased OS rate and CS rate of colorectal cancer.

Association between insulin therapy and risk of liver cancer among diabetics: a meta-analysis of epidemiological studies

As the results of the association between insulin therapy and risk of liver cancer among diabetics have been inconsistent in epidemiological studies, we conducted a meta-analysis to quantify this issue. Data of relevant epidemiological studies were collected by searching articles in PubMed, Web of Science, and Embase till 29 June 2017. Random-effects models were employed to combine study-specific risks. Five cohort studies and nine case-control studies were included in our meta-analysis with 285 008 patients with diabetes mellitus and 4329 liver cancer cases. When we compared insulin-use group with noninsulin use group in patients with diabetes mellitus, we observed a statistically significant association between insulin therapy and liver cancer, with an overall relative risk of 1.90 (95% confidence interval: 1.44-2.50, I=76.1%). We did not find heterogeneity between subgroups stratified by study characteristics and adjusted confounders, except for subgroups related to 'follow-up years' of cohort studies. The combined estimate was robust across sensitivity analysis, and no publication bias was detected. Our results indicated that insulin therapy was associated with elevated incidence of liver cancer among diabetics. Given the high prevalence of diabetes, avoiding excess or unnecessary insulin use to control the blood glucose may offer a potential public health benefit in reducing liver cancer risk. Further studies are warranted to investigate the types, doses, and treatment duration of insulin use in large sample size or cohort of diabetic patients.

Pancreatic volume is reduced in patients with latent autoimmune diabetes in adults

AIMS

This study aimed to compare pancreatic volume and its clinical significance among patients with type 2 diabetes mellitus (DM), adult-onset type 1 DM and latent autoimmune diabetes in adults (LADA).

METHODS

This is a cross-sectional study. One hundred twenty-six outpatients (68 with LADA and 58 with type 1 DM) and 158 inpatients (71 with type 2 DM and 87 non-diabetic controls) were recruited during May-July 2013 in Shanghai Jiao Tong University Affiliated Sixth People's Hospital. All the patients underwent abdominal computerized tomography; pancreatic volume was then calculated.

RESULTS

The mean pancreatic volume was highest in the controls, followed by those in patients with type 2 DM, LADA and type 1 DM. The pancreatic volume in LADA was comparable with that in type 2 DM but significantly greater than that in type 1 DM (p < 0.05). The pancreatic volume in patients with LADA was significantly correlated with sex, waist circumference, body surface area, body mass index, diastolic blood pressure and high-density lipoprotein cholesterol (all p < 0.05). The correlation between pancreatic volume and fasting C-peptide was high in patients with LADA (r = 0.643, p < 0.001) and moderate in patients with type 2 DM (r = 0.467, p < 0.001). The area under the receiver operating characteristic curve for pancreatic volume predictive of absolute insulin deficiency (FCP < 0.9 ng/mL) was 0.85 (0.76-0.94) in LADA.

CONCLUSIONS

Pancreatic atrophy in LADA was less marked than in type 1 DM. Pancreatic atrophy may suggest reduced level of fasting C-peptide in patients with LADA. Copyright © 2016 John Wiley & Sons, Ltd.

Incidence and Mortality Risks of Cancer in Patients with Type 2 Diabetes: A Retrospective Study in Shanghai, China

Background: Evidence from epidemiologic investigation indicates that people with type 2 diabetes (T2DM) are at a significantly higher risk of many types of cancer and mortality. The aim of this study was to investigate the incidence and mortality risks of cancer in patients with T2DM compared with the general population in Shanghai, China. Methods: Based on the Shanghai Diabetes Registry (SDR) database linking to the Shanghai Cancer Registry and Surveillance System (SCRSS), a total of 12,276 T2DM patients without cancer were defined and followed up from 1 December 2001 to 31 July 2011. Standardized incidence ratio (SIR) and standardized mortality ratio (SMR) with 95% confidence interval (CI) were calculated using the whole gender and age-matched general population of Shanghai as a reference during the same period. Results: The overall cancer risk was found higher in both males and females T2DM patients, with the SIR of 3.14 (95% CI 2.73–3.56) and 4.29 (95% CI 3.64–4.94), respectively. The overall mortality risk of cancer also significantly increased with the SMR of 2.27 (95% CI 1.86–2.68) and 1.86 (95% CI 1.46–2.26), respectively. Pancreatic cancer was with the highest SIR and SMR in both genders. Conclusions: Compared with the general population, patients with T2DM were associated with higher incidence and mortality risks of cancer, especially pancreatic cancer.

Evidence for DNA damage as a biological link between diabetes and cancer

Objective:

This review examines the evidence that: Diabetes is a state of DNA damage; pathophysiological factors in diabetes can cause DNA damage; DNA damage can cause mutations; and DNA mutation is linked to carcinogenesis.

Data Sources:

We retrieved information from the PubMed database up to January, 2014, using various search terms and their combinations including DNA damage, diabetes, cancer, high glucose, hyperglycemia, free fatty acids, palmitic acid, advanced glycation end products, mutation and carcinogenesis.

Study Selection:

We included data from peer-reviewed journals and a textbook printed in English on relationships between DNA damage and diabetes as well as pathophysiological factors in diabetes. Publications on relationships among DNA damage, mutagenesis, and carcinogenesis, were also reviewed. We organized this information into a conceptual framework to explain the possible causal relationship between DNA damage and carcinogenesis in diabetes.

Results:

There are a large amount of data supporting the view that DNA mutation is a typical feature in carcinogenesis. Patients with type 2 diabetes have increased production of reactive oxygen species, reduced levels of antioxidant capacity, and increased levels of DNA damage. The pathophysiological factors and metabolic milieu in diabetes can cause DNA damage such as DNA strand break and base modification (i.e., oxidation). Emerging experimental data suggest that signal pathways (i.e., Akt/tuberin) link diabetes to DNA damage. This collective evidence indicates that diabetes is a pathophysiological state of oxidative stress and DNA damage which can lead to various types of mutation to cause aberration in cells and thereby increased cancer risk.

Conclusions:

This review highlights the interrelationships amongst diabetes, DNA damage, DNA mutation and carcinogenesis, which suggests that DNA damage can be a biological link between diabetes and cancer.

Determinants of mortality in patients with type 2 diabetes: a review

We aimed to review and summarize the evidence from accomplished trials analyzing factors influencing mortality in patients with T2DM and to provide some recommendations for targets and treatment in the European region. The following databases were searched for relevant trials: PubMed and the Cochrane Library. Of 3.806 citations, 134 trials met our inclusion criteria.

RESULTS

The reduction in lifetime for 65 + -years-old patients having less than 10 years T2DM amounts to 1.8 years. Having T2DM for more than 10 years lifetime will be reduced by 2.7 years. However, the lifetime shortening factor of T2DM will even be stronger for 40 + -years-old patients at onset. Males will lose 11.6 years of life and 18.6 QUALYs. T2DM among females will reduce life by 14 QUALYs by 22 years. From a statistical point of view, the highest mortality rate will occur in an over 55-years-old European smoking and non-compliant diabetic woman with alcohol abuse living in a rural area with a low level of education and a low socio-economic status. Furthermore, other co-morbidities such as cardiovascular diseases, gout, and depression affect mortality. Additionally, mortality will increase with a BMI over 35 and also with a BMI under 20-25. This refers to the obesity paradox indicating a higher mortality rate among normal weight patients with T2DM compared to overweight patients with T2DM. HbA1c-levels between 6.5 % and 7 % are associated with the lowest impact on mortality.

Treatment with insulin (analogues) and breast cancer risk in diabetics; a systematic review and meta-analysis of in vitro, animal and human evidence

INTRODUCTION

Several studies have suggested that anti-diabetic insulin analogue treatment might increase cancer risk. The aim of this study was to review the postulated association between insulin and insulin analogue treatment and breast cancer development, and plausible mechanisms.

METHOD

A systematic literature search was performed on breast cell-line, animal and human studies using the key words 'insulin analogue' and 'breast neoplasia' in MEDLINE at PubMed, EMBASE, and ISI Web of Science databases. A quantitative and qualitative review was performed on the epidemiological data; due to a limited number of reported estimates, a meta-analysis was performed for glargine only. A comprehensive overview was composed for in vitro and animal studies. Protein and gene expression was analysed for the cell lines most frequently used in the included in vitro studies.

RESULTS

In total 16 in vitro, 5 animal, 2 in vivo human and 29 epidemiological papers were included. Insulin AspB10 showed mitogenic properties in vitro and in animal studies. Glargine was the only clinically available insulin analogue for which an increased proliferative potential was found in breast cancer cell lines. However, the pooled analysis of 13 epidemiological studies did not show evidence for an association between insulin glargine treatment and an increased breast cancer risk (HR 1.04; 95 % CI 0.91-1.17; p=0.49) versus no glargine in patients with diabetes mellitus. It has to be taken into account that the number of animal studies was limited, and epidemiological studies were underpowered and suffered from methodological limitations.

CONCLUSION

There is no compelling evidence that any clinically available insulin analogue (Aspart, Determir, Glargine, Glulisine or Lispro), nor human insulin increases breast cancer risk. Overall, the data suggests that insulin treatment is not involved in breast tumour initiation, but might induce breast tumour progression by up regulating mitogenic signalling pathways.

Association between body mass index and diabetic retinopathy in Chinese patients with type 2 diabetes

AIMS

To explore the factors mediating the relationship between body mass index (BMI) and diabetic retinopathy (DR) in Chinese type 2 diabetes patients.

METHODS

This is a cross-sectional study. Data of 2,533 patients with type 2 diabetes were studied from the Shanghai Diabetes Registry Database. DR was assessed using non-mydriatic fundus photography and graded as non-DR, mild-moderate (DR I-II), and sight-threatening (DR III-IV). BMI (kg/m(2)) was classified as normal weight (18.5 ≤ BMI < 25), overweight (25 ≤ BMI < 30), and obese (BMI ≥ 30). β cell function was evaluated by fasting C-peptide (FCP).

RESULTS

DR was present in 701 (27.7 %) patients. Patients with DR had lower BMI (24.3 vs. 24.9 kg/m(2), P = 0.001) and fasting C-peptide (1.46 vs. 1.86 ng/ml, P < 0.001) than those without DR. The association between BMI (2 kg/m(2) interval) and DR was U-shaped; patients with BMI 28-29.9 kg/m(2) had the lowest DR rate. Compared with normal weight, overweight was associated with reduced risk of any DR [odds ratio (OR) 0.73], DR I-II (OR 0.76), and DR III-IV (OR 0.64) after adjustment for sex, age at diabetes diagnosis, and duration of diabetes. This negative association attenuated after adjustment for other confounders and became nonsignificant after further adjustment for FCP. Patients with different BMI categories had similar DR risk when stratified by FCP tertiles.

CONCLUSION

Overweight patients have lower DR prevalence than normal weight individuals, which may be attributable to better β cell function in overweight patients.

Anti-diabetic medications do not influence risk of lung cancer in patients with diabetes mellitus: a systematic review and meta-analysis

OBJECTIVES

Several preclinical and observational studies have shown that anti-diabetic medications (ADMs) may modify the risk of lung cancer. We performed a systematic review and meta-analysis evaluating the effect of metformin, sulfonylureas (SUs), thiazolidinediones (TZDs), and insulin on the risk of lung cancer in patients with diabetes mellitus (DM).

MATERIALS AND METHODS

We conducted a systematic search of Pubmed and Web of Science, up to August 20, 2013. We also searched the Conference Proceedings Citation Index (CPCI) and China National Knowledge Infrastructure (CNKI) for abstracts from major meetings. Fixed or random effect pooled measures were selected based on heterogeneity among studies, which was evaluated using Q test and the I2 of Higgins and Thompson. Meta-regression was used to explore the sources of between-study heterogeneity. Publication bias was analyzed by Begg's funnel plot and Egger's regression test. Associations were assessed by odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

A total of 15 studies (11 cohort, 4 case-control) were included in this meta-analysis. In observational studies no significant association between metformin (n=11 studies; adjusted OR=0.99, 95%CI: 0.87-1.12), SUs (n=5 studies; adjusted OR=0.98, 95%CI: 0.79-1.22), or TZDs (n=7 studies; adjusted OR=0.92, 95%CI: 0.75-1.13), insulin (n=6 studies; adjusted OR=1.13, 95%CI: 0.79-1.62) use and risk of developing lung cancer was noted. There was considerable inherent heterogeneity between studies not explained by study design, setting, or location.

CONCLUSIONS

Meta-analysis of existing studies does not support a protective or harmful association between ADMs use and risk of lung cancer in patients with DM. There was considerable heterogeneity across studies, and future, well-designed, prospective studies would be required for better understanding of any association.

Antidiabetic drugs and risk of cancer

Antidiabetic drugs are an important group of medications used worldwide. They differ from each other in the mechanisms of lowering blood glucose as well as in adverse effects that may affect the course of the treatment and its efficacy. In recent years, new drugs have been discovered in order to improve the maintenance of proper blood glucose level and to reduce unwanted effects of these drugs. Their growing administration is related to the increasing incidence of diabetes observed in all countries in the world. Epidemiological data indicate that diabetes increases the risk of cancer, as well as the risk of death linked with neoplasms. It is still unknown whether this is an effect of antidiabetic drugs or just the effect of diabetes itself. In recent years there have been numerous investigations and meta-analyzes, based on both comparative and cohort studies trying to establish the relationship between antidiabetic pharmacotherapy and the incidence and mortality due to cancer. According to their findings, most of antidiabetic drugs increase the risk of cancer while only few of them show antitumor properties. Different mechanisms of action of glucose-lowering drugs may be responsible for these effects. However, most of the published studies concerning the influence of these drugs on cancer incidence were designed with some limitations and differed from each other in the approach. In this review, we discuss the association between antidiabetic drugs used in monotherapy or polytherapy and cancer risk, and consider potential mechanisms responsible for the observed effects.

Insulin therapy and the risk of colorectal cancer in patients with type 2 diabetes: a meta-analysis of observational studies

AIMS

Several epidemiological studies have reported inconsistent associations between insulin therapy and the risk of colorectal cancer (CRC) in patients with type 2 diabetes mellitus. We performed this meta-analysis of observational studies to evaluate the effect of insulin therapy on the risk of CRC.

METHODS

We carried out a systematic search of PubMed, Embase and the Cochrane Library Central database between January 1966 and August 2013. Fixed-effects and random-effects models were used to estimate the pooled relative risk (RR) and corresponding 95% confidence interval (CI).

RESULTS

A total of 12 epidemiological studies were included in the present meta-analysis, involving a total of 7947 CRC cases and 491 384 participants. There was significant heterogeneity among the studies, but no publication bias. Insulin therapy significantly increased the risk of CRC [RR = 1.69, 95% CI (1.25, 2.27)]. When the various studies were stratified by study design, we found that insulin use was associated with a statistically significant 115% higher risk of CRC among case-control studies [RR = 2.15, 95% CI (1.41, 3.26)], but not among cohort studies [RR = 1.25, 95% CI (0.95, 1.65)]. Furthermore, a significant association was noted among studies conducted in USA [RR = 1.73, 95% CI (1.15, 2.60)] and Asia [RR = 2.55, 95% CI (2.14, 3.04)], but not in Europe [RR = 1.20, 95% CI (0.92, 1.57)].

CONCLUSIONS

The present meta-analysis suggests that insulin therapy may increase the risk of CRC. More prospective cohort studies with longer follow-up durations are warranted to confirm this association. Furthermore, future studies should report results stratified by gender and race and should adjust the results by more confounders.

The association between type 2 diabetes mellitus and women cancer: the epidemiological evidences and putative mechanisms

Type 2 diabetes mellitus (T2DM), a chronic disease increasing rapidly worldwide, is well established as an important risk factor for various types of cancer. Although many factors impact the development of T2DM and cancer including sex, age, ethnicity, obesity, diet, physical activity levels, and environmental exposure, many epidemiological and experimental studies are gradually contributing to knowledge regarding the interrelationship between DM and cancer. The insulin resistance, hyperinsulinemia, and chronic inflammation associated with diabetes mellitus are all associated strongly with cancer. The changes in bioavailable ovarian steroid hormone that occur in diabetes mellitus (the increasing levels of estrogen and androgen and the decreasing level of progesterone) are also considered potentially carcinogenic conditions for the breast, endometrium, and ovaries in women. In addition, the interaction among insulin, insulin-like growth factors (IGFs), and ovarian steroid hormones, such as estrogen and progesterone, could act synergistically during cancer development. Here, we review the cancer-related mechanisms in T2DM, the epidemiological evidence linking T2DM and cancers in women, and the role of antidiabetic medication in these cancers.

Diabetes and cancer: A critical appraisal of the pathogenetic and therapeutic links

Diabetes and cancer represent two common, multifactorial, chronic and potentially fatal diseases, not infrequently co-diagnosed in the same patient. Epidemiological data demonstrate significant increases of the cancer incidence in patients with obesity and diabetes, which is more evident for certain site-specific cancers. Although there is increasing evidence that strongly indicates an augmented risk of cancer in diabetic patients, several confounding factors complicate the ability to precisely assess the risk. Mainly in insulin-resistant states (such as in type 2 diabetes mellitus and in metabolic syndrome), direct associations between obesity-related hyperinsulinemia and increasing circulating insulin-like growth factor-1 (IGF-1) levels have been implicated as key factors in the mechanisms involved in carcinogenesis. Whilst anti-diabetic drugs can increase the cancer risk, anti-proliferative drugs may cause diabetes or aggravate pre-existing diabetes. Additionally, an increasing number of targeted anti-cancer therapies may interfere with the pathways shared by IGF-1 and insulin receptors, showing a adverse effect on glucose metabolism through various mechanisms. Although there is a requirement for large-scale randomized evidence, the present review summarizes the majority of the epidemiological association studies between diabetes and various types of cancer, discussing the pathophysiological mechanisms that may be involved in promoting carcinogenesis in diabetes and the potential impact of different anti-diabetic therapies on cancer risk.

Conventional hypoglycaemic agents and the risk of lung cancer in patients with diabetes: a meta-analysis

BACKGROUND

Accumulating evidence suggests that hypoglycaemic agents influence lung cancer risk in patients with diabetes. It remains to be fully elucidated whether conventional hypoglycaemic agents (metformin, sulfonylureas, thiazolidinediones [TZDs] or insulin) affect lung cancer incidence in patients with diabetes.

METHODS

We performed a meta-analysis using EMBASE, MEDLINE and Web of Science to search randomised controlled trials (RCTs), cohort studies, and case-control studies published up to October 2013 that assessed the effects of metformin, sulfonylurea, TZDs or insulin on lung cancer risk in subjects with diabetes. Fixed and random effects meta-analysis models were used, and the effect size was expressed as a summary odds ratio (OR) with 95% confidence intervals (CI). The Grades of Research, Assessment, Development and Evaluation (GRADE) approach was applied to define the quality of the evidence.

RESULTS

Analysis of 15 studies (11 cohort studies, 2 case-control studies, and 2 RCTs) showed that metformin use was associated with a 15% reduction in risk of lung cancer (OR 0.85, 95% CI 0.77 to 0.92), but this finding was not supported by sub-analysis of smoking-adjusted studies (OR 0.84, 95% CI 0.61 to 1.06). Moreover, sulfonylurea or TZDs use was not associated with increased or decreased lung cancer risk, respectively (OR 1.10, 95% CI 0.93 to 1.26), (OR 0.86, 95% CI 0.70 to 1.02). Higher lung cancer risk was related to insulin (OR 1.23, 95% CI 1.10 to 1.35). However, all data from RCTs failed to demonstrate a statistically significant effect.

CONCLUSIONS

This analysis demonstrated that metformin use may reduce lung cancer risk in patients with diabetes but not in a smoking-adjusted subgroup and that insulin use may be associated with an increased lung cancer risk in subjects with diabetes.

Insulin therapy and colorectal cancer risk among type 2 diabetes mellitus patients: a systemic review and meta-analysis

BACKGROUND

Insulin is widely used in patients with type 2 diabetes mellitus (T2DM). More attention was focused on its higher risk of colorectal cancer (CRC). This meta-analysis examined the relationship between levels of insulin use and the risk of CRC.

METHODS

A meta-analysis using data from 12 published epidemiologic studies (7 case-control, and 5 cohort studies) published before Jan. 2014 was done to examine the association between insulin use and CRC. Random effects analyses were done to calculate relative risk (RR) and 95% confidence intervals (CI). Heterogeneity among studies was measured by the χ2 and I2 statistic.

RESULTS

Overall, the risk of CRC was significantly associated with insulin use to a random-effects model (RR, 1.69; 95% CI, 1.25 -2.27). When subgroup analyses were conducted according to the study types, no associations were detected in cohort group (RR, 1.25; 95% CI, 0.95-1.65; I2, 75.7%); however significant association was detected in case-control group (RR, 2.15; 95% CI, 1.41-3.26; I2, 89.1%).

CONCLUSIONS

A significant harmful effect of insulin, observed mainly among case-control studies, may result from study design differences and amount of included studies. Although these results suggest a harmful effect of insulin use for CRC risk, additional large studies are warranted to support these preliminary evidences.

VIRTUAL SLIDES

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2194715731194123.

Effect of aerobic exercise on peripheral nerve functions of population with diabetic peripheral neuropathy in type 2 diabetes: a single blind, parallel group randomized controlled trial

OBJECTIVE

To evaluate the effect of moderate intensity aerobic exercise (40%-60% of Heart Rate Reserve (HRR)) on diabetic peripheral neuropathy.

METHODS

A parallel-group, randomized controlled trial was carried out in a tertiary health care setting, India. The study comprised of experimental (moderate intensity aerobic exercise and standard care) and control groups (standard care). Population with type 2 diabetes with clinical neuropathy, defined as a minimum score of seven on the Michigan Diabetic Neuropathy Score (MDNS), was randomly assigned to experimental and control groups by computer generated random number tables. RANOVA was used for data analysis (p<0.05 was significant).

RESULTS

A total of 87 patients with DPN were evaluated in the study. After randomization there were 47 patients in the control group and 40 patients in the experimental group. A comparison of two groups using RANOVA for anthropometric measures showed an insignificant change at eight weeks. For distal peroneal nerve's conduction velocity there was a significant difference in two groups at eight weeks (p<0.05), Degrees of freedom (Df)=1, 62, F=5.14, and p=0.03. Sural sensory nerve at eight weeks showed a significant difference in two groups for conduction velocity, Df =1, 60, F=10.16, and p=0.00. Significant differences in mean scores of MDNS were also observed in the two groups at eight weeks (p value significant<0.05).

CONCLUSION

Moderate intensity aerobic exercises can play a valuable role to disrupt the normal progression of DPN in type 2 diabetes.

Insulin therapy and risk of colorectal cancer: an updated meta-analysis of epidemiological studies

OBJECTIVE

An increasing number of studies show that exogenous insulin therapy may promote colorectal carcinogenesis. However, the results of the association between insulin therapy and risk of colorectal cancer (CRC) among type 2 diabetes patients are inconsistent. The purpose of our study is to examine the effect of insulin therapy on CRC risk among patients with type 2 diabetes in an updated meta-analysis.

RESEARCH DESIGN AND METHODS

Medline and Embase were searched for the reference lists of pertinent articles published from January 1970 to April 2013. Two investigators independently extracted the data and reached consensus on the inclusion and exclusion criteria. Pooled relative risks and 95% confidence intervals were calculated with a random-effects model.

RESULTS

Analysis of six studies, including 374,950 participants, showed that compared with non-insulin or metformin treatment, insulin treatment was associated with an increase of 37% in the risk of colorectal neoplasm among patients with type 2 diabetes, with moderate heterogeneity (I2=40%). The sensitivity analysis showed that exclusion of one small case-control study had no appreciable changes on the pooled results. Subgroup analyses suggested that there were significant positive associations between insulin therapy and risk of CRC in some subgroups, rather than all subgroups.

CONCLUSIONS

Our meta-analysis supports a relationship between insulin therapy and increased risk of CRC in patients with type 2 diabetes. Because of bias and confounding of included studies, caution is needed when interpreting our results. Further investigations are needed.

Diabetes and cancer relationships

Diabetes and cancer are both heterogeneous and multifactorial diseases with tremendous impact on health worldwide. Epidemiologic evidence suggests that certain malignancies may be associated with diabetes, as well as with diabetes risk factors and, perhaps, with certain diabetes treatments. Numerous biological mechanisms could account for these relationships. Insulin-like growth factor (IGF)-1, IGF-2, IGF-1 receptors, insulin, and the insulin receptor play roles in the development and progression of cancers. Although evidence from randomized controlled trials does not support or refute associations of diabetes and its treatments with either increased or reduced risk of cancer incidence or prognosis, consideration of malignancy incidence rates and the magnitude of the trials that would be required to address these issues explains why such studies may not be readily undertaken.

Insulin therapy and risk of prostate cancer: a systematic review and meta-analysis of observational studies

BACKGROUND

Previous observational studies have shown that insulin therapy may modify the risk of prostate cancer (PCa). However, these studies yielded controversial results. Thus, we performed this meta-analysis to determine whether insulin use was associated with PCa risk in patients with diabetes mellitus (DM).

METHOD

A literature search was carried out in PubMed, EMBASE, and Cochrane Library Central database between January 1966 and January 2013. Fixed-effect and random-effect models were used to estimate pooled relative risks (RR) and corresponding 95% confidence intervals (CIs). Subgroup analyses and sensitivity analyses were also performed.

RESULT

A total of 11 (10 cohorts, and one case-control) studies published between 2007 and 2013 were included in the meta-analysis, representing data for 205,523 male subjects and 7,053 PCa cases. There were five studies investigating the influence of insulin and other glucose-lowering agents on the risk of PCa , and six studies investigating the influence of glargine and non-glargine insulin. Insulin use was not associated with PCa risk when compared with other glucose-lowering agents (RR=0.89, 95% CI, 0.72-1.09). Use of insulin glargine did not contribute to susceptibility to PCa as compared with use of non-glargine insulin (RR=1.26, 95% CI, 0.86-1.84). Sensitivity analysis confirmed the stability of present results, since no individual study affected the pooled result significantly.

CONCLUSIONS

Our results suggest that, there may be no significant association between insulin use and risk of PCa as compared with other glucose-lowering agents in patients with DM, and there was no substantial evidence for increase risk of PCa among insulin glargine users as compared to non-glargine insulin users. Further studies are warranted to validate these conclusions.