Insulin glargine and risk of cancer: a cohort study in the French National Healthcare Insurance Database

Diabetes and cancer: a 2013 synopsis

Diabetes, in particular type 2 diabetes, and cancer are two diseases that appear to be associated. Numerous epidemiological studies indicate indeed that diabetes increases the incidence of several tumors. Chronic hyperglycemia and/or insulin resistance with compensatory hyperinsulinemia could account for the association. On the other hand, the interpretation of the link between diabetes and cancer could be influenced by therapeutical interferences. Considering all these data together, cancer should be considered as a "new potential complication" of diabetes and integrated in the follow-up of diabetic subjects.

Antidiabetic medications and the risk of colorectal cancer in patients with diabetes mellitus: a systematic review and meta-analysis

BACKGROUND

Antidiabetic medications (ADM) may modify colorectal cancer risk in patients with diabetes mellitus. We performed a systematic review and meta-analysis, evaluating the effect of metformin, thiazolidinediones (TZD), sulfonylureas, and insulin on colorectal cancer risk in diabetic patients.

METHODS

We conducted a systematic search of multiple bibliographic databases, up to September 2012, for articles that evaluated exposure to metformin, TZD, sulfonylureas, and insulin, reported colorectal cancer risk in patients with diabetes mellitus, and reported OR or provided data for their estimation. Summary OR estimates with 95% confidence intervals (CI) were estimated using the random-effects model.

RESULTS

Fifteen studies reporting 13,871 cases of colorectal cancer in 840,787 patients with diabetes mellitus were included. Meta-analysis of observational studies showed an 11% reduction in colorectal cancer risk associated with metformin use (n = 9 studies; OR, 0.89; 95% CI, 0.81-0.99), whereas TZD use was not associated with colorectal cancer risk (n = 5 studies; OR, 0.96; 95% CI, 0.87-1.05). Conversely, a trend toward higher colorectal cancer risk was observed with sulfonylurea (n = 7 studies; OR, 1.11; 95% CI, 0.97-1.26) and insulin (n = 9 studies; OR, 1.33; 95% CI, 0.91-1.94) use, although these associations were not statistically significant. There was considerable heterogeneity across studies, partly explained by study location and adjustment for concomitant use of other ADMs. Post-hoc analysis of randomized controlled trials did not reveal any significant association between ADM and colorectal cancer risk.

CONCLUSIONS

Meta-analysis of published studies supports a protective association between metformin use and colorectal cancer risk in patients with diabetes mellitus.

IMPACT

Clinical trials on the chemopreventive effect of metformin against colorectal cancer are warranted.

Insulin use and smoking jointly increase the risk of bladder cancer mortality in patients with type 2 diabetes

BACKGROUND

Whether insulin use predicts bladder cancer mortality has not been investigated. Furthermore, it is not known whether insulin use and smoking jointly influence the risk.

MATERIALS AND METHODS

A total of 86,939 patients (40,014 men, 46,925 women) with type 2 diabetes mellitus (T2DM) and aged ≥ 25 years in a nationally representative cohort were followed prospectively from 1995 to 2006 for bladder cancer mortality. Cox regression was used considering the following independent variables: age, sex, diabetes duration, body mass index, smoking, insulin use, and area of residence. The models were created for patients aged ≥ 25 and ≥ 65 years, separately; and sensitivity analyses were conducted after excluding (1) patients with duration between onset of diabetes and bladder cancer mortality < 5 years, and (2) patients with diabetes duration at recruitment < 3 years. The joint effect of insulin use and smoking was evaluated.

RESULTS

Patients who died of bladder cancer were characterized by older age, male predominance, longer diabetes duration, smoking, and insulin use. In multivariable Cox models, age, male sex, and insulin use were consistently predictive for bladder cancer mortality in all analyses, whereas the other variables were not. The adjusted hazard ratios for bladder cancer mortality for insulin users vs. nonusers ranged from 1.877 to 2.502 in different models (all P values < .05). Insulin use and smoking jointly increased the adjusted hazard ratio to 3.120 (95% confidence interval, 1.329-7.322).

CONCLUSIONS

Insulin use is significantly predictive for bladder cancer mortality in patients with T2DM. Insulin use and smoking jointly increase the risk.

The Relationship between Metformin and Cancer in Patients with Type 2 Diabetes

BACKGROUND

Recently, several studies reported that the cancer incidence in type 2 diabetes patients is higher than in the general population. Although a number of risks are shared between cancer and diabetes patients, there have been few studies of its correlation. We evaluated the influences of several factors including low density lipoprotein cholesterol (LDL-C), albuminuria and use of metformin on the risk of cancer in patients with type 2 diabetes.

METHODS

We enrolled 1,320 patients with at least 5 years of follow-up and 73 patients were diagnosed with cancer during this period. The associations of the risk factors with cancer incidence were evaluated by multiple regression analysis. The subjects were placed into two subgroups based on metformin dosage (<1,000 mg/day, ≥1,000 mg/day) and we compared cancer incidence using analysis of covariance.

RESULTS

LDL-C and albuminuria were not significantly correlated with cancer risk. In contrast, metformin showed a reverse correlation with cancer risk (P=0.006; relative risk, 0.574). In the metformin nonadministration group, smoking, male gender, and high triglyceride levels tended to be contributing factors without statistical significance. Cancer occurence was lower in the low dose metformin group (less than 1,000 mg/day) (P=0.00).

CONCLUSION

These results suggest that the administration of low dose metformin in patients with type 2 diabetes may be associated with a reduced risk of cancer.

Glargine safety, diabetes and cancer

INTRODUCTION

In 2009, several epidemiological studies suggested a higher frequency of malignancy in insulin glargine -treated patients. A number of follow-up epidemiological population studies as well as two randomized, controlled clinical studies, one a 5000-patient retinopathy study and the other a 12,000-patient cardiovascular outcomes trial (ORIGIN), found no higher frequency of malignancy in glargine-treated patients.

AREAS COVERED

We reviewed the existing literature as well as U.S. FDA records to investigate the association of cancer, diabetes, and insulin. There is a 20 - 40% higher incidence of malignancy in type 2 diabetes patients. Certain cancers are more common, including hepatocellular and pancreatic carcinoma, colorectal cancer, renal cancer, and breast and endometrial cancer, and non-Hodgkin's lymphoma. There are numerous inter-related factors which may promote both diabetes and malignancy, including dietary patterns, obesity, insulin resistance, and alcoholism. Patients who receive insulin treatment are typically older and "sicker" than those who receive oral agents.

EXPERT OPINION

It is very difficult to prove causal associations between diabetes and cancer due to the host of confounding factors. The hypothesis that hyperinsulinemia and IGF-1 receptor activation promote cancer is strong, but confounded by the association of hyperinsulinemia with obesity, which separately promotes malignancy. Although statistical techniques to adjust for confounding variables can improve epidemiological comparisons, the lesson of the glargine cancer controversy is that controlled clinical trials are the only means to definitely prove hypotheses.

The metabolic and mitogenic properties of basal insulin analogues

CONTEXT

Retrospective, observational studies have reported an association between diabetes treatment with insulin and a higher incidence of cancer.

OBJECTIVE

Overview the literature for in vitro and in vivo studies of the metabolic and mitogenic properties of basal insulin analogues and assess the implications for clinical use.

METHODS

Relevant studies were identified through PubMed and congress abstract database searches; data on metabolic and mitogenic signalling in relation to insulin treatment of diabetes are included in this review.

RESULTS

The balance of evidence shows that although some analogues have demonstrated mitogenic potency in some in vitro studies in cancer cell lines, these findings do not translate to the in vivo setting in animals or to the clinical setting in humans.

CONCLUSIONS

The current consensus is that there is no clinical or in vivo evidence to indicate that any commercially available insulin analogue has carcinogenic effects. Large-scale, prospective clinical and observational studies will further establish any potential link.

Does insulin glargine increase the risk of cancer compared with other basal insulins?: A French nationwide cohort study based on national administrative databases

OBJECTIVE

To explore in France the relationship between insulin glargine use and overall and specific cancer risks in type 2 diabetic patients compared with other basal insulins.

RESEARCH DESIGN AND METHODS

Data were extracted from French health insurance information system (Système National d'Information Inter-Régimes de l'Assurance Maladie) linked with data from the French Hospital Discharge database (Programme de Médicalisation des Systèmes d'Information). Included were 70,027 patients aged 40-79 years who started a basal insulin in 2007-2009. Cox proportional hazards models with age as time-scale were used to calculate multivariate-adjusted hazard ratios for associations between type of basal insulin and risk of overall cancer, breast cancer, and seven other cancer sites.

RESULTS

The median follow-up was 2.67 years in patients exposed to insulin glargine. Absolute event rates for all cancer in patients exposed to glargine versus other basal insulin users were 1,622 and 1,643 per 100,000 person-years, respectively. No significant association was observed between glargine exposure and overall cancer incidence after adjustment for sex, with a hazard ratio of 0.97 (95% CI 0.87-1.07), or after additional adjustment for any other hypoglycemic agent use and duration of diabetes. No increased risk of breast cancer was observed for glargine users compared with other basal insulins users, with a fully adjusted hazard ratio of 1.08 (0.72-1.62).

CONCLUSIONS

In a large cohort of patients newly treated by basal insulin, no increased risk of any cancer was observed in insulin glargine users compared with other basal insulin users. Because follow-up did not exceed 4 years, longer-term studies are needed.

Insulin glargine and cancer risk in patients with diabetes: a meta-analysis

AIM

The role of insulin glargine as a risk factor for cancer is controversial in human studies. The aim of this meta-analysis was to evaluate the relationship between insulin glargine and cancer incidence.

METHODS

All observational studies and randomized controlled trials evaluating the relationship of insulin glargine and cancer risk were identified in PubMed, Embase, Web of Science, Cochrane Library and the Chinese Biomedical Medical Literature Database, through March 2012. Odds ratios (ORs) with corresponding 95% confidence interval (CI) were calculated with a random-effects model. Confidence in the estimates of the obtained effects (quality of evidence) was assessed by using the Grading of Recommendations Assessment, Development, and Evaluation approach.

RESULTS

A total of 11 studies including 448,928 study subjects and 19,128 cancer patients were finally identified for the meta-analysis. Insulin glargine use was associated with a lower odds of cancer compared with non-glargine insulin use (OR 0.81, 95% CI 0.68 to 0.98, P = 0.03; very low-quality evidence). Glargine did not increase the odds of breast cancer (OR 0.99, 95% CI 0.68 to 1.46, P = 0.966; very low-quality evidence). Compared with non-glargine insulin, no significant association was found between insulin glargine and prostate cancer, pancreatic cancer and respiratory tract cancer. Insulin glargine use was associated with lower odds of other site-specific cancer.

CONCLUSIONS

Results from the meta-analysis don't support the link between insulin glargine and an increased risk of cancer and the confidence in the estimates of the effects is very low. Further studies are needed to examine the relation between insulin glargine and cancer risk, especially breast cancer.

Diabetes, obesity and cancer: risk and anti-risk factors

Observable diabetes and obesity epidemics may result in alteration of cancer morbidity and mortality. This increasingly recognized problem is reviewed here from the perspective of interplay between factors that differently modify association of diabetes mellitus with malignant neoplasms. Heterogeneity and familial aspects of diabetes and obesity, genomic traits, anti-diabetic medications and weight-reducing treatment are important examples of such factors. Addressing them might promote development of efficient preventive measures.

Design of non-standard insulin analogs for the treatment of diabetes mellitus

Structure-based protein design has enabled the engineering of insulin analogs with improved pharmacokinetic and pharmacodynamic properties. Exploiting classical structures of zinc insulin hexamers, the first insulin analog products focused on destabilization of subunit interfaces to obtain rapid-acting (prandial) formulations. Complementary efforts sought to stabilize the insulin hexamer or promote higher-order self-assembly within the subcutaneous depot toward the goal of enhanced basal glycemic control with reduced risk of hypoglycemia. Current products either operate through isoelectric precipitation (insulin glargine, the active component of Lantus; Sanofi-Aventis, Paris, France) or employ an albumin-binding acyl tether (insulin detemir, the active component of Levemir; Novo-Nordisk, Basværd, Denmark). In the past year second-generation basal insulin analogs have entered clinical trials in an effort to obtain ideal flat 24-hour pharmacodynamic profiles. The strategies employ non-standard protein modifications. One candidate (insulin degludec; Novo-Nordisk a/s) undergoes extensive subcutaneous supramolecular assembly coupled to a large-scale allosteric reorganization of the insulin hexamer (the TR transition). Another candidate (LY2605541; Eli Lilly and Co., Indianapolis, IN, USA) utilizes coupling to polyethylene glycol to delay absorption and clearance. On the other end of the spectrum, advances in delivery technologies (such as microneedles and micropatches) and excipients (such as the citrate/zinc-ion chelator combination employed by Biodel, Inc., Danbury, CT, USA) suggest strategies to accelerate PK/PD toward ultra-rapid-acting insulin formulations. Next-generation insulin analogs may also address the feasibility of hepatoselective signaling. Although not in clinical trials, early-stage technologies provide a long-range vision of "smart insulins" and glucose-responsive polymers for regulated hormone release.

Insulin therapy and cancer in type 2 diabetes

Despite the availability of many other agents, insulin is widely used as a treatment for type 2 diabetes. In vitro, insulin stimulates the growth of cancer cells, through the interaction with insulin-like growth factor-1 (IGF-1) receptors and its own receptors. In observational surveys on type 2 diabetes, insulin therapy is associated with an increased incidence of several forms of cancer, although it is difficult to discriminate the effect of confounders from that of insulin itself. Randomized trials do not confirm the increased risk associated with insulin therapy, although they do not allow to rule out some negative effects on specific forms of cancer, at least at higher doses. Among insulin analogues, glargine has a higher affinity for the IGF-1 receptor and a greater mitogenic potency in vitro than human insulin, but it is extensively metabolized in vitro to products with low IGF-1 receptor affinity. Overall, epidemiological studies suggest a possible increase of risk with glargine, with respect to human insulin, only at high doses and for some forms of cancer (i.e., breast). Data from clinical trials do not confirm, but are still insufficient to totally exclude, such increased risk. However, beneficial effects of insulin outweigh potential cancer risks.

Diabetes, glucose control, glucose lowering medications, and cancer risk: a 10-year population-based historical cohort

Background

Both diabetes and glucose-lowering medications have been associated with an increased risk of cancer incidence. This study will compare cancer incidence rates in individuals with and without diabetes; and will investigate, in individuals with diabetes, an association between glucose control and cancer incidence; and between the use of specific glucose-lowering medications, as well as no drug exposure, and cancer incidence.

Methods/design

This is a population based historical cohort study of all individuals aged 21 years or older (about 2,300,000) who were insured by Clalit Health Services, the largest health maintenance organization in Israel during a ten-year study period. Four study groups will be established according to the status of diabetes and cancer at study entry, Jan 1, 2002: cancer free, diabetes free; cancer free, diabetes prevalent; cancer prevalent, diabetes free; and cancer prevalent, diabetes prevalent. Individuals without diabetes at study entry will be followed for diabetes incidence, and all four groups will be followed for specific cancer incidence, including second primary neoplasms. Glucose control will be assessed by HbA1c and by fasting plasma glucose levels. Time dependent regression models for cancer incidence will account for glucose-lowering medications as they are added and changed over the follow-up period. A large number of demographic and clinical variables will be considered, including: age, gender, BMI, smoking status, concomitant medications, glucose control (assessed by HbA1c and by fasting plasma glucose) and cancer screening tests.

Discussion

Strengths of this study include the large population; high quality comprehensive data; comparison to individuals without diabetes, and to those with diabetes but not treated with glucose-lowering medications; and the extensive range of variables available for analysis. The great increases in diabetes prevalence and in treatment options render this study particularly relevant and timely. The Israeli national healthcare system, characterized by high standard and uniform healthcare, offers an advantageous environment for its conduct.

Optimizing treatment strategies with insulin glargine in Type 2 diabetes

Advances in insulin therapy have made a positive contribution to improving disease management in both Type 1 and Type 2 diabetes. The development of insulin analogs with time-action characteristics has made it easier to mimic physiological insulin secretion. The parallel improvement in delivery devices has also made insulin therapy more convenient, flexible and acceptable. The inevitable progression of Type 2 diabetes means that the majority of those people will also require insulin therapy at some point in their disease course. Current treatment options are many; when to initiate insulin and which regimen to choose are among the major questions confronting physicians in today's rapidly evolving environment. This article summarizes the current strategies for initiating and optimizing the use of the basal insulin analog, insulin glargine, in Type 2 diabetes, leading to the intermediate stage of insulin therapy with the introduction of meal-related, rapid-acting insulin analogs in a stepwise manner prior to a full replacement basal-bolus regimen.

Diabetes medications and cancer risk: review of the literature

BACKGROUND

Cancer and diabetes are major public health problems for the United States and the world. Diabetes remains the leading cause of blindness, kidney failure, and nontraumatic lower limb amputation, whereas cancer continues to be a major cause of death, accounting for approximately 1 of 4 deaths in the United States. Recently, a potential link between diabetes and cancer has been suggested in the medical literature.

OBJECTIVE

To review the current literature on any potential link between diabetes medications and the risk for cancer.

DISCUSSION

Increasing evidence suggests that diabetic patients are at increased risk of developing cancer. The exact mechanism for the increased cancer risk in patients with diabetes is unknown. Because of a potential correlation between diabetes and cancer, studies are emerging that evaluate the cancer risk of medications used to treat diabetes. This article reviews the current data in the literature regarding the association between the various drug classes indicated for the treatment of diabetes and cancer development or prevention.

CONCLUSION

Despite many studies showing a correlation between some medications for diabetes and the development of cancer, there is no clear evidence of a direct causation between these drugs and cancer. Therefore, providers and patients should continue to use medications to control diabetes as before, because the correlation between uncontrolled diabetes and cancer is stronger than the correlation between medications for diabetes and cancer.

Insulin Degludec, The New Generation Basal Insulin or Just another Basal Insulin?

The advances in recombinant DNA technology have led to an improvement in the properties of currently available long-acting insulin analogs. Insulin degludec, a new generation ultra-long-acting basal insulin, currently in phase 3 clinical trials, has a promising future in clinical use. When compared to its rival basal insulin analogs, a longer duration of action and lower incidence of hypoglycemic events in both type 1 and type 2 diabetic patients has been demonstrated.1,2 Its unique mechanism of action is based on multihexamer formation after subcutaneous injection. This reportedly allows for less pharmacodynamic variability and within-subject variability than currently available insulin analogs, and a duration of action that is over 24 hours.3 The lack of proof of carcinogenicity with insulin degludec is yet another factor that would be taken into consideration when choosing the optimal basal insulin for a diabetic individual.4 A formulation of insulin degludec with insulin aspart, Insulin degludec 70%/aspart 30%, may permit improved flexibly of dosing without compromising glycemic control or safety.5.

Insulin analogs for the treatment of diabetes mellitus: therapeutic applications of protein engineering

The engineering of insulin analogs represents a triumph of structure-based protein design. A framework has been provided by structures of insulin hexamers. Containing a zinc-coordinated trimer of dimers, such structures represent a storage form of the active insulin monomer. Initial studies focused on destabilization of subunit interfaces. Because disassembly facilitates capillary absorption, such targeted destabilization enabled development of rapid-acting insulin analogs. Converse efforts were undertaken to stabilize the insulin hexamer and promote higher-order self-assembly within the subcutaneous depot toward the goal of enhanced basal glycemic control with reduced risk of hypoglycemia. Current products either operate through isoelectric precipitation (insulin glargine, the active component of Lantus(®); Sanofi-Aventis) or employ an albumin-binding acyl tether (insulin detemir, the active component of Levemir(®); Novo-Nordisk). To further improve pharmacokinetic properties, modified approaches are presently under investigation. Novel strategies have recently been proposed based on subcutaneous supramolecular assembly coupled to (a) large-scale allosteric reorganization of the insulin hexamer (the TR transition), (b) pH-dependent binding of zinc ions to engineered His-X(3)-His sites at hexamer surfaces, or (c) the long-range vision of glucose-responsive polymers for regulated hormone release. Such designs share with wild-type insulin and current insulin products a susceptibility to degradation above room temperature, and so their delivery, storage, and use require the infrastructure of an affluent society. Given the global dimensions of the therapeutic supply chain, we envisage that concurrent engineering of ultra-stable protein analog formulations would benefit underprivileged patients in the developing world.