Treatment with insulin glargine (Lantus) increases the proliferative potency of the serum of patients with type-1 diabetes: a pilot study on MCF-7 breast cancer cells

Role of metformin and other metabolic drugs in the prevention and therapy of endocrine-related cancers

Metabolic syndrome is associated with chronic diseases, including type 2 diabetes, cardiovascular diseases, and cancer. This review summarizes the current evidence on the antitumor effects of some relevant drugs currently used to manage metabolic-related pathologies (i.e. insulin and its analogs, metformin, statins, etc.) in endocrine-related cancers including breast cancer, prostate cancer, pituitary cancer, ovarian cancer, and neuroendocrine neoplasms. Although current evidence does not provide a clear antitumor role of several of these drugs, metformin seems to be a promising chemopreventive and adjuvant agent in cancer management, modulating tumor cell metabolism and microenvironment, through both AMP-activated protein kinase-dependent and -independent mechanisms. Moreover, its combination with statins might represent a promising therapeutic strategy to tackle the progression of endocrine-related tumors. However, further studies are needed to endorse the clinical relevance of these drugs as adjuvants for cancer chemotherapy.

The Impact of Diabetes Mellitus on the Second Primary Malignancies in Colorectal Cancer Patients

Introduction

All colorectal cancer (CRC) survivors have an increased risk of developing second primary malignancies (SPMs). The association between diabetes mellitus (DM) and the risk of cancer is well known. However, the role of DM and its therapy in the development of SPMs in CRC patients is not well described.

Methods

In this single-institutional retrospective analysis we identified 1,174 colorectal carcinoma patients, median follow-up 10.1 years, (median age 63 years, 724 men). All patients over 18 years with histologically confirmed CRC who were admitted in the period 1.1. 2003- 31.12.2013 and followed-up till 31.12. 2018 at the Masaryk Memorial Cancer Institute (MMCI) were screened for eligibility. The exclusion criteria were CRC diagnosed at autopsy, lost to follow-up and high risk of development of SPMs due to hereditary cancer syndrome. Tumours are considered multiple primary malignancies if arising in different sites and/or are of a different histology or morphology group. Comparisons of the basic characteristics between the patients with SPM and the patients without SPM were performed as well as comparison of the occurrence of SPMs by the site of diagnosis between the DM and non-DM cohorts and survival analyses.

Results

A SPM was diagnosed in 234 (20%) patients, DM in 183 (15%) patients. DM was diagnosed in 22.6% of those with SPM vs. in 13.8% of those without SPM (p=0.001). The most common types of SPMs in DM patients were other CRC, kidney, lung, bladder and nonmelanoma skin cancer, but only carcinoma of the liver and bile duct tracts was significantly more common than in the group without DM. Although breast cancer was the second most common in the group with DM, its incidence was lower than in the group without DM, as well as prostate cancer. A significantly higher incidence of SPMs was found in older CRC patients (≥ 65 years) and in those with lower stage colon cancer and DM. No significant difference in DM treatment between those with and without a SPM was observed including analysis of type of insulin.

Conclusion

CRC patients with diabetes mellitus, especially those with older age, and early stages of colon cancer, should be screened for second primary malignancies more often than the standard population. Patients without DM have longer survival. According to the occurrence of the most common second malignancies, a clinical examination, blood count, and ultrasound of the abdomen is appropriate, together with standard breast and colorectal cancer screening, and lung cancer screening under certain conditions, and should be recommended in CRC survivors especially in patients with intercurrent DM, however the necessary frequency of screening remains unclear.

Cancer Biology and Prevention in Diabetes

The available evidence suggests a complex relationship between diabetes and cancer. Epidemiological data suggest a positive correlation, however, in certain types of cancer, a more complex picture emerges, such as in some site-specific cancers being specific to type I diabetes but not to type II diabetes. Reports share common and differential mechanisms which affect the relationship between diabetes and cancer. We discuss the use of antidiabetic drugs in a wide range of cancer therapy and cancer therapeutics in the development of hyperglycemia, especially antineoplastic drugs which often induce hyperglycemia by targeting insulin/IGF-1 signaling. Similarly, dipeptidyl peptidase 4 (DPP-4), a well-known target in type II diabetes mellitus, has differential effects on cancer types. Past studies suggest a protective role of DPP-4 inhibitors, but recent studies show that DPP-4 inhibition induces cancer metastasis. Moreover, molecular pathological mechanisms of cancer in diabetes are currently largely unclear. The cancer-causing mechanisms in diabetes have been shown to be complex, including excessive ROS-formation, destruction of essential biomolecules, chronic inflammation, and impaired healing phenomena, collectively leading to carcinogenesis in diabetic conditions. Diabetes-associated epithelial-to-mesenchymal transition (EMT) and endothelial-to-mesenchymal transition (EndMT) contribute to cancer-associated fibroblast (CAF) formation in tumors, allowing the epithelium and endothelium to enable tumor cell extravasation. In this review, we discuss the risk of cancer associated with anti-diabetic therapies, including DPP-4 inhibitors and SGLT2 inhibitors, and the role of catechol-o-methyltransferase (COMT), AMPK, and cell-specific glucocorticoid receptors in cancer biology. We explore possible mechanistic links between diabetes and cancer biology and discuss new therapeutic approaches.

Long-acting insulin analogs and cancer

AIMS

Hyperinsulinemia is a recognized risk factor for cancer and plays a major role for the increased cancer incidence in diabetic patients. Whether insulin analogs, and particularly long-acting analogs, worsen the pro-cancer effect of excess insulin is still controversial.

DATA SYNTHESIS

In this paper we summarize the biological bases for the potential detrimental effect of long-acting analogs on cancer cells and review the in vitro and in vivo evidence on this issue. Because of their different molecular structure relative to native insulin, insulin analogs may activate the insulin receptor (IR) and the post receptor pathways differently. Most, but not all, in vitro evidence indicate that long-acting analogs may have a stronger mitogenic potency than insulin on cancer cells. Notably insulin glargine, the most studied long-acting analog, also has a higher affinity for the insulin-like growth factor (IGF)-1 receptor, a potent growth mediator. In vitro observations, however, may not reflect what occurs in vivo when analogs are metabolized to derivatives with a different mitogenic activity. Clinical studies, mostly retrospective and predominantly concerning glargine, provide contrasting results. The only perspective trial found no cancer increase in patients treated with glargine. All these studies, however, have severe weaknesses because of the insufficient evaluation of important factors such as dose administered, length of exposure, patient follow-up duration and site-specific cancer investigation. Moreover, whether cancer promotion is a long-acting analog class characteristic or a specific effect of a single agent is not clear.

CONCLUSIONS

In conclusion the carcinogenic risk of long-acting analogs, and specifically glargine, can be neither confirmed nor excluded. A personalized and shared decision, considering all the individual risk factors (metabolic and non-metabolic), is the suggestion for the clinician.

Effects of insulin and analogues on carcinogen-induced mammary tumours in high-fat-fed rats

It is not fully clarified whether insulin glargine, an analogue with a high affinity for insulin-like growth factor-1 receptor (IGF-1R), increases the risk for cancers that abundantly express IGF-1R such as breast cancer or some types of breast cancer. To gain insight into this issue, female Sprague-Dawley rats fed a high-fat diet were given the carcinogen N-methyl-N-nitrosourea and randomly assigned to vehicle (control), NPH (unmodified human insulin), glargine or detemir (n = 30 per treatment). Insulins were given subcutaneously (15 U/kg/day) 5 days a week. Mammary tumours were counted twice weekly, and after 6 weeks of treatment, extracted for analysis. None of the insulin-treated groups had increased mammary tumour incidence at any time compared with control. At 6 weeks, tumour multiplicity was increased with NPH or glargine (P < 0.05) and tended to be increased with detemir (P = 0.2); however, there was no difference among insulins (number of tumours per rat: control = 0.8 ± 0.1, NPH = 1.8 ± 0.3, glargine = 1.5 ± 0.4, detemir = 1.4 ± 0.4; number of tumours per tumour-bearing rat: control = 1.3 ± 0.1, NPH = 2.2 ± 0.4, glargine = 2.7 ± 0.5, detemir = 2.3 ± 0.5). IGF-1R expression in tumours was lower than that in Michigan Cancer Foundation-7 (MCF-7) cells, a cell line that shows greater proliferation with glargine than unmodified insulin. In rats, glargine was rapidly metabolised to M1 that does not have greater affinity for IGF-1R. In conclusion, in this model of oestrogen-dependent breast cancer in insulin-resistant rats, insulin and insulin analogues increased tumour multiplicity with no difference between insulin types.

Impaired glucose metabolism treatment and carcinogenesis

Carbohydrate metabolism disorders increase the risk of carcinogenesis. Diabetes mellitus alters numerous physiological processes that may encourage cancer growth. However, treating impaired glucose homeostasis may actually promote neoplasia; maintaining proper glucose plasma concentrations reduces metabolic stresses, however, certain medications may themselves result in oncogenic effects. A number of previous studies have demonstrated that metformin reduces the cancer risk. However, the use of sulfonylurea derivatives correlates with an increased risk of developing a malignancy. Another form of treatment, insulin therapy, involves using various forms of insulin that differ in pharmacodynamics, pharmacokinetics and efficacy. Previous studies have indicated that certain insulin variants also affect the cancer risk. The results from analyses that address the safety of long-lasting insulin types raise the most concern regarding the increased risk of malignancy. Rapid development of novel diabetic medications and their widespread use carries the risk of potentially increased rates of cancer, unnoticeable in limited, randomized, controlled trials. In the present review, the results of clinical and epidemiological studies are evaluated to assess the safety of anti-hyperglycemic medications and their effect on cancer risk and outcomes.

Associations between diabetes medication use and risk of second breast cancer events and mortality

PURPOSE

Diabetes and certain diabetes medications have been shown to influence breast cancer (BC) risk. Less is known about their relation to BC outcomes. Our objective was to evaluate the effects of diabetes and diabetes medications on risk of second breast cancer events (SBCE) and mortality.

METHODS

This population-based cohort study was conducted among women diagnosed with early-stage (I-II) BC and enrolled in an integrated health plan. Exposures of interest were diabetes and medication classes including insulin, metformin, and sulfonylureas. Outcomes of interest were SBCE defined as recurrence or second primary BC, BC-specific mortality, and all-cause mortality. We used multivariable Cox proportional hazards models to estimate hazard ratios (HR) and 95 % confidence intervals (CI) for diabetes and medication use while accounting for potential confounders and competing risks.

RESULTS

Among 4,216 women, 13 % developed SBCE during a median follow-up of 6.3 years. 610 women had diabetes of which 76 % used oral diabetes medication and/or insulin. Findings suggested that diabetes increased the risk of recurrence (HR = 1.57; 95 % CI 1.09-2.25) but not overall SBCE (HR = 1.29; 95 % CI 0.94-1.76) or second primary BC (HR = 0.74; 95 % CI 0.39-1.41). Among women with diabetes, insulin use was associated with increased risks of recurrence (HR = 1.94; 95 % CI 1.08-3.48) and all-cause mortality (HR = 2.33; 95 % CI 1.70-3.20). Metformin use was associated with lower all-cause mortality (HR = 0.55; 95 % CI 0.38-0.79).

CONCLUSIONS

Our findings show an association between diabetes and increased recurrence risk, and risk may be greater among insulin users. Metformin may reduce all-cause mortality among BC survivors. Given the growing breast cancer survivor population, further research in larger, more diverse populations is warranted.

Insulin analogues display atypical differentiative activities in skin keratinocytes

BACKGROUND

We have previously shown that both insulin and IGF1 lead to increased proliferation of keratinocytes. However, whereas insulin supports keratinocytes differentiation, IGF1 inhibits this process. The aim of the present study was to examine the proliferative and differentiative effects of insulin analogues (glargine, detemir, lispro and aspart) in primary keratinocytes in comparison with insulin and IGF1.

METHODS

Primary keratinocytes cultures were produced from newborn BALB/c mice skin. Proliferation rates were assessed by [(3)H]-thymidine incorporation and XTT assays and differentiation was evaluated by Western blots analysis. Insulin receptor and IGF1 receptor phosphorylation was assessed by immunoprecipitation assays.

RESULTS

Treatment with glargine or detemir resulted in an insulin-like effect on the differentiation process whereas lispro and aspart treatment led to an IGF1-like effect. In addition, treatment of keratinocytes with aspart led to a rapid phosphorylation of the IGF1 receptor.

CONCLUSIONS

Our study provides evidence that insulin analogues elicit atypical actions in the skin.

Cancer biology in diabetes

Diabetes is a serious metabolic disease that causes multiple organ dysfunctions. Recent evidence suggests that diabetes could contribute to the initiation and progression of certain cancers in addition to the classic diabetic complications. Furthermore, some of the drugs used clinically to treat patients with diabetes might affect cancer initiation, progression and mortality. The recent discovery of the possible anticancer effects of metformin, a classic antidiabetic drug, has led physicians and scientists to reconsider the interaction between diabetes and cancer. In the present review, we analyze recent reports in this field, and explore possible mechanistic links between diabetes and cancer biology.

Development of a human breast-cancer derived cell line stably expressing a bioluminescence resonance energy transfer (BRET)-based phosphatidyl inositol-3 phosphate (PIP3) biosensor

Stimulation of tyrosine kinase receptors initiates a signaling cascade that activates PI3K. Activated PI3K uses PIP2 to generate PIP3, which recruit Akt to the plasma membrane through its pleckstrin homology (PH) domain, permitting its activation by PDKs. Activated Akt controls important biological functions, including cell metabolism, proliferation and survival. The PI3K pathway is therefore an attractive target for drug discovery. However, current assays for measurement of PIP3 production are technically demanding and not amenable to high-throughput screening. We have established a MCF-7-derived breast cancer cell line, that stably co-expresses the PH domain of Akt fused to Renilla luciferase and YFP fused to a membrane localization signal. This BRET biosensor pair permits to monitor, in real time, in living cells, PIP3 production at the plasma membrane upon stimulation by different ligands, including insulin, the insulin analogue glargine, IGF1, IGF2 and EGF. Moreover, several known inhibitors that target different steps of the PI3K/Akt pathway caused inhibition of ligand-induced BRET. Cetuximab, a humanized anti-EGF receptor monoclonal antibody used for the treatment of cancer, completely inhibited EGF-induced BRET, and the tyrosine kinase inhibitor tyrphostine AG1024 inhibited insulin effect on PIP3 production. Moreover, the effects of insulin and IGF1 were inhibited by molecules that inhibit PI3K catalytic activity or the interaction between PIP3 and the PH domain of Akt. Finally, we showed that human serum induced a dose-dependent increase in BRET signal, suggesting that this stable clone may be used as a prognostic tool to evaluate the PI3K stimulatory activity present in serum of human patients. We have thus established a cell line, suitable for the screening and/or the study of molecules with stimulatory or inhibitory activities on the PI3K/Akt pathway that will constitute a new tool for translational research in diabetes and cancer.

Insulin glargine versus other types of basal insulin-clinical and tumor characteristics in patients with breast carcinoma

Background

Recent epidemiological studies have suggested that some insulin analogues could be associated with an increased risk of cancer. The aim of this retrospective study was to examine whether patients with diabetes mellitus (DM) using insulin glargine have a higher tumor stage of breast carcinoma in comparison to patients using other types of insulin.

Methods

We performed a chart review of 79 surgically treated breast carcinoma patients (mean age of 66.5 years; range 38-86 years) who were on insulin. Insulin glargine was used in 13 patients, while the other 66 patients were on other types of insulin. Clinical and histopathology characteristics of patients on glargine versus other types of insulin were compared using a chi-square test and non-parametric statistical analysis.

Results

DM type 1 and DM type 2 was present in 14 and 65 patients, respectively. The mean tumor size was 2.98 cm. The TNM tumor stage at diagnosis was not higher among patients on glargine compared to patients on other types of insulin (T1/T2 85% vs. 68%, T3/T4 15% vs. 32%, p = 0.32; N1 54% vs. 58%, p = 0.80; M1 8% vs. 6%, respectively). No significant differences between both study groups (glargine vs. other types of insulin) were found in the ages of the patients, their BMI, tumor histology, grade, number of metastatic lymph nodes, hormone receptors or HER-2 status.

Conclusion

We could not show that patients with DM using insulin glargine have a higher tumor stage of breast carcinoma in comparison to those using other types of insulin.

The epidemiology and molecular mechanisms linking obesity, diabetes, and cancer

The worldwide epidemic of obesity is associated with increasing rates of the metabolic syndrome and type 2 diabetes. Epidemiological studies have reported that these conditions are linked to increased rates of cancer incidence and mortality. Obesity, particularly abdominal obesity, is associated with insulin resistance and the development of dyslipidemia, hyperglycemia, and ultimately type 2 diabetes. Although many metabolic abnormalities occur with obesity and type 2 diabetes, insulin resistance and hyperinsulinemia appear to be central to these conditions and may contribute to dyslipidemia and altered levels of circulating estrogens and androgens. In this review, we will discuss the epidemiological and molecular links between obesity, type 2 diabetes, and cancer, and how hyperinsulinemia and dyslipidemia may contribute to cancer development. We will discuss how these metabolic abnormalities may interact with estrogen signaling in breast cancer growth. Finally, we will discuss the effects of type 2 diabetes medications on cancer risk.

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.

Differential impact of structurally different anti-diabetic drugs on proliferation and chemosensitivity of acute lymphoblastic leukemia cells

Hyperglycemia during hyper-CVAD chemotherapy is associated with poor outcomes of acute lymphoblastic leukemia (ALL) (Cancer 2004; 100: 1179-85). The optimal clinical strategy to manage hyperglycemia during hyper-CVAD is unclear. To examine whether anti-diabetic pharmacotherapy can influence chemosensitivity of ALL cells, we examined the impacts of different anti-diabetic agents on ALL cell lines and patient samples. Pharmacologically achievable concentrations of insulin, aspart and glargine significantly increased the number of ALL cells, and aspart and glargine did so at lower concentrations than human insulin. In contrast, metformin and rosiglitazone significantly decreased the cell number. Human insulin and analogs activated AKT/mTOR signaling and stimulated ALL cell proliferation (as measured by flow cytometric methods), but metformin and rosiglitazone blocked AKT/mTOR signaling and inhibited proliferation. Metformin 500 μM and rosiglitazone 10 μM were found to sensitize Reh cells to daunorubicin, while aspart, glargine and human insulin (all at 1.25 mIU/L) enhanced chemoresistance. Metformin and rosiglitazone enhanced daunorubicin-induced apoptosis, while insulin, aspart and glargine antagonized daunorubicin-induced apoptosis. In addition, metformin increased etoposide-induced and L-asparaginase-induced apoptosis; rosiglitazone increased etoposide-induced and vincristine-induced apoptosis. In conclusion, our results suggest that use of insulins to control hyperglycemia in ALL patients may contribute to anthracycline chemoresistance, while metformin and thiazolidinediones may improve chemosensitivity to anthracycline as well as other chemotherapy drugs through their different impacts on AKT/mTOR signaling in leukemic cells. Our data suggest that the choice of anti-diabetic pharmacotherapy during chemotherapy may influence clinical outcomes in ALL.

A fully human, allosteric monoclonal antibody that activates the insulin receptor and improves glycemic control

Many patients with diabetes mellitus (both type 1 and type 2) require therapy to maintain normal fasting glucose levels. To develop a novel treatment for these individuals, we used phage display technology to target the insulin receptor (INSR) complexed with insulin and identified a high affinity, allosteric, human monoclonal antibody, XMetA, which mimicked the glucoregulatory, but not the mitogenic, actions of insulin. Biophysical studies with cultured cells expressing human INSR demonstrated that XMetA acted allosterically and did not compete with insulin for binding to its receptor. XMetA was found to function as a specific partial agonist of INSR, eliciting tyrosine phosphorylation of INSR but not the IGF-IR. Although this antibody activated metabolic signaling, leading to enhanced glucose uptake, it neither activated Erk nor induced proliferation of cancer cells. In an insulin resistant, insulinopenic model of diabetes, XMetA markedly reduced elevated fasting blood glucose and normalized glucose tolerance. After 6 weeks, significant improvements in HbA(1c), dyslipidemia, and other manifestations of diabetes were observed. It is noteworthy that hypoglycemia and weight gain were not observed during these studies. These studies indicate, therefore, that allosteric monoclonal antibodies have the potential to be novel, ultra-long acting, agents for the regulation of hyperglycemia in diabetes.

Addition of insulin glargine or NPH insulin to metformin monotherapy in poorly controlled type 2 diabetic patients decreases IGF-I bioactivity similarly

AIMS/HYPOTHESIS

The aim of this study was to compare IGF-I bioactivity 36 weeks after the addition of insulin glargine (A21Gly,B31Arg,B32Arg human insulin) or NPH insulin to metformin therapy in type 2 diabetic patients who had poor glucose control under metformin monotherapy.

METHODS

In the Lantus plus Metformin (LANMET) study, 110 poorly controlled insulin-naive type 2 diabetic patients were randomised to receive metformin with either insulin glargine (G+MET) or NPH insulin (NPH+MET). In the present study, IGF-I bioactivity was measured, retrospectively, in 104 out of the 110 initially included LANMET participants before and after 36 weeks of insulin therapy. IGF-I bioactivity was measured using an IGF-I kinase receptor activation assay.

RESULTS

After 36 weeks of insulin therapy, insulin doses were comparable between the G+MET (68 ± 5.7 U/day) and NPH+MET (71 ± 6.2 U/day) groups (p = 0.68). Before insulin therapy, circulating IGF-I bioactivity was similar between the G+MET (134 ± 9 pmol/l) and NPH+MET (135 ± 10 pmol/l) groups (p = 0.83). After 36 weeks, IGF-I bioactivity had decreased significantly (p = 0.001) and did not differ between the G+MET (116 ± 9 pmol/l) and NPH+MET (117 ± 10 pmol/l) groups (p = 0.91). At baseline and after insulin therapy, total IGF-I concentrations were comparable in both groups (baseline: G+MET 13.3 ± 1.0 vs NPH+MET 13.3 ± 1.0 nmol/l, p = 0.97; and 36 weeks: 13.4 ± 1.0 vs 13.1 ± 0.9 nmol/l, p = 0.71). Total IGF-I concentration did not change during insulin therapy (13.3 ± 0.7 vs 13.3 ± 0.7 nmol/l, baseline vs 36 weeks, p = 0.86).

CONCLUSIONS/INTERPRETATION

Addition of insulin glargine or NPH insulin to metformin monotherapy in poorly controlled type 2 diabetic patients decreases serum IGF-I bioactivity in a similar manner.

Insulins: past, present, and future

This article highlights selected milestones in insulin discovery and its continued development as a pivotal therapy for diabetes. The last 90 years have witnessed tremendous progress in insulin therapy, from the initial crude, yet life-saving, animal insulin extracts to novel human insulin analogues. Although the complete physiologic replacement of insulin is inherently difficult to achieve with open-loop subcutaneously administered insulin, the continued development of improved injectable insulin formulations with superior pharmacokinetics and pharmacodynamics will enhance glucose control, and represents important clinical advances in the treatment of both type 1 and type 2 diabetes.

Risk of cancer in patients on insulin glargine and other insulin analogues in comparison with those on human insulin: results from a large population-based follow-up study

AIMS/HYPOTHESIS

Several publications suggest an association between certain types of insulin and cancer, but with conflicting results. We investigated whether insulin glargine (A21Gly,B31Arg,B32Arg human insulin) is associated with an increased risk of cancer in a large population-based cohort study.

METHODS

Data for this study were obtained from dispensing records from community pharmacies individually linked to hospital discharge records from 2.5 million individuals in the Netherlands. In a cohort of incident users of insulin, the association between insulin glargine and other insulin analogues, respectively, and cancer was analysed in comparison with human insulin using Cox proportional hazard models with cumulative duration of drug use as a time-varying determinant. The first hospital admission with a primary diagnosis of cancer was considered as the main outcome; secondary analyses were performed with specific cancers as outcomes.

RESULTS

Of the 19,337 incident insulin users enrolled, 878 developed cancer. Use of insulin glargine was associated with a lower risk of malignancies in general in comparison with human insulin (HR 0.75, 95% CI 0.71, 0.80). In contrast, an increased risk was found for breast cancer (HR 1.58, 95% CI 1.22, 2.05). Dose-response relationships could not be identified.

CONCLUSION/INTERPRETATION

Users of insulin glargine and users of other insulin analogues had a lower risk of cancer in general than those using human insulin. Both associations might be a consequence of residual confounding, lack of adherence or competing risk. However, as in previous studies, we demonstrated an increased risk of breast cancer in users of insulin glargine in comparison with users of human insulin.

New insulins and insulin therapy

The introduction of the so-called 'designer' insulins, the insulin analogues, has offered new opportunities in the clinical management of diabetes. Two additional new entities are close to reaching clinical practice. Linjeta™ (formally called VIAject) is not an analogue but rather a different formulation of human insulin which may give it a more rapid onset of action, potentially even faster than the currently available rapid-acting insulin analogues. Degludec™, on the other hand, is an insulin analogue molecule with an ultra-long clinical profile derived from the soluble multi-hexamer formation, resulting in a continuous slow and stable release of insulin degludec monomers which may last longer than currently available long-acting analogues. As with any new type of drug, the safety of the 'designer' insulins has to be closely scrutinised. Last year the increased cancer risk in diabetes entered the spotlight and the potential role of insulin analogues led to controversial discussions. In spite of recent new in vitro and observational data no new conclusive evidence became available. The need for multiple well-conducted and appropriately designed prospective observational studies to follow up the effectiveness and safety of the new insulins and the new insulin treatment regimens remains. In this chapter it was our mission to chose articles published about "new insulins" over the last year that have the most important contribution for the on-going development of ultra-fast- and ultra-long-acting insulin analogs and preparations and their potential side-effects, particularly cancer. This has been done by means of PubMed searches as well as a review of abstracts of the recent large international diabetes meetings such as ADA, EASD and ISPAD.

Long-term effects of insulin glargine on the risk of breast cancer

AIMS/HYPOTHESIS

There have been growing concerns regarding the long-term effects of insulin glargine (A21Gly,B31Arg,B32Arg human insulin) on the risk of breast cancer.

METHODS

We used the UK's General Practice Research Database (GPRD) to identify a cohort of women aged 40 years or over with type 2 diabetes, treated with insulin during 2002-2006 and followed until the first breast cancer diagnosis or 31 December 2009. After the users of insulin glargine had been matched with users of other insulins on age, calendar time and duration of prior insulin use, the HR of breast cancer associated with insulin glargine use was estimated using a Cox proportional hazards model, adjusted for known risk factors for breast cancer.

RESULTS

The cohort comprised 15,227 women, including 4,579 glargine users and 10,648 users of other insulins, of which 246 developed breast cancer during up to 8 years follow-up (incidence rate 4.1 per 1,000 per year). Insulin glargine use was not associated with an increased risk of breast cancer during the first 5 years of use (HR 0.9; 95% CI 0.7-1.3). The risk tended to increase after 5 years (HR 1.8; 95% CI 0.8-4.0), and significantly so for the women who had been on insulin before starting glargine (HR 2.7; 95% CI 1.1-6.5).

CONCLUSIONS/INTERPRETATION

The risk of breast cancer in women with type 2 diabetes is not increased during the first 5 years of insulin glargine use. However, longer-term use may increase this risk, particularly in women with longstanding use of insulin before starting insulin glargine.

Insulin therapy in diabetes and cancer risk: current understanding and implications for future study: proceedings from a meeting of a European Insulin Safety Consensus Panel, convened and sponsored by Novo Nordisk, held Tuesday October 5, 2010 at The Radisson Edwardian Heathrow Hotel, Hayes, Middlesex, UK

INTRODUCTION

Interest in the possibility of certain insulin treatments having the potential to modify cancer development and prognosis was reawakened in 2009, following publication of several epidemiological studies addressing this issue. This interest extends to how diabetes itself and cancer might be linked, and makes desirable an exchange of expert views and knowledge to enhance understanding in this subject among those treating diabetes and cancer, or those developing diabetes therapies.

METHODS

A European meeting was convened with participants invited based on known relevant interests in endocrinology, oncology, epidemiology, and insulin analog design and investigation. Experts in these fields were invited to present on relevant topics, with open discussions held after each presentation.

RESULTS

Concern over the potential mitogenic properties of certain insulin analogs has arisen from some (but not all) epidemiological studies, although confounding factors render interpretation controversial. Future epidemiological studies are likely to strengthen confidence in drawing conclusions. Meanwhile, pharmacological studies, and a consideration of cancer pathophysiology, implicate increased insulin-like growth factor-1 receptor affinity, and/or deranged insulin receptor interaction/signaling properties as possible a priori causes for concern with some insulin analogs. Again, interpretation of the body of pharmacological evidence is confounded by the array of test systems and methodologies used, and by studies frequently succumbing to methodological pitfalls. Reassuringly, most available insulin analogs do not differ in their receptor interaction response profile to human insulin, and for those that do there are reasons to question any potential clinical relevance. Nevertheless, it is desirable that new experimental models are devised that can better determine the likely clinical consequences of any variance in receptor response profile versus human insulin.

CONCLUSION

More data are required to increase our understanding of this issue. To facilitate and disseminate such understanding, close cooperation and communication between diabetologists, epidemiologists, oncologists, and insulin engineers will be essential.

Basal insulin: physiology, pharmacology, and clinical implications

Primary goals in the treatment of type 2 diabetes mellitus (T2DM) include lowering blood glucose levels sufficiently to prevent micro- and macrovascular complications while limiting side effects, such as hypoglycemia and excessive weight gain. Patients with T2DM are typically treated initially with oral antidiabetes agents; however, as the disease progresses, most will require insulin to maintain glycemic control. Often insulin therapy is initiated with basal insulin, and the objective of this article is to present the conceptual aspects of basal insulin therapy and use these concepts to illustrate important clinical aspects. This will be accomplished within a broader contextual discussion of the normal physiologic patterns of insulin secretion, which consist of sustained levels of basal insulin production throughout the day, superimposed with bursts of insulin secretion following a meal (termed bolus or prandial insulin secretion) that slowly decay over 1 to 3 hours. Long-acting basal insulin analogs form a key component of basal-bolus therapy and provide basal support for patients with T2DM. Insulin therapy is often initiated with basal insulin, and newer long-acting analogs, such as insulin glargine and insulin detemir, provide steady, reliable basal insulin coverage in addition to significant advantages over traditional long-acting insulins. This article will integrate conceptual aspects of basal insulin therapy in the context of physiology, molecular pharmacology, and clinical implications of modern basal insulin analogs to provide a foundational understanding of basal insulin biology and physiology.

Cancer incidence in type 2 diabetes patients - first results from a feasibility study of the D2C cohort

BACKGROUND

A large prospective study in patients with type 2 diabetes (T2D), the German D2C cohort, is presently being enumerated to investigate risk factors of incident cancer in diabetic patients.

STUDY SETTING

A disease management program was offered, on a voluntary basis, to all T2D patients who were members of a statutory health insurance fund in Germany. This first feasibility report uses data from 26.742 T2D patients, who were 40 to 79 years old, resided in the Muenster District, and who were enrolled between June 2003 and July 2008. Cancer cases were identified through the regional Cancer Registry.

METHODS

Invasive cancer cases were identified using probabilistic record linkage procedures and pseudonymised personal identifiers. Censoring date was December 31, 2008. We included only first cancers, leaving 12.650 male and 14.092 female T2D with a total of 88.778 person-years (py). We computed standardised incidence ratios (SIR) for external comparisons and we employed Cox regression models and hazard ratios (HR) within the cohort.

RESULTS

We identified 759 first cancers among male T2D patients (18.7 per 1,000 py) and 605 among females (12.7 per 1,000 py). The risk of any incident cancer in T2D was raised (SIR = 1.14; 95% confidence interval [1.10 - 1.21]), in particular for cancer of the liver (SIR = 1.94 [1.15 - 2.94]) and pancreas (SIR = 1.45 [1.07-1.92]). SIRs decreased markedly with time after T2D diagnosis. In Cox models, adjusting for diabetes duration, body mass index and sex, insulin therapy was related to higher cancer risk (HR = 1.25 [1.17 - 1.33]). No effect was seen for metformin.

DISCUSSION

Our study demonstrates feasibility of record linkage between DMP and cancer registries. These first cohort results confirm previous reports. It is envisaged to enhance this cohort by inclusion of further regions of the state, expansion of the follow-up times, and collection of a more detailed medication history.

Differences in bioactivity between human insulin and insulin analogues approved for therapeutic use- compilation of reports from the past 20 years

In order to provide comprehensive information on the differences in bioactivity between human insulin and insulin analogues, published in vitro comparisons of human insulin and the rapid acting analogues insulin lispro (Humalog®), insulin aspart ( NovoRapid®), insulin glulisine (Apidra®), and the slow acting analogues insulin glargine (Lantus®), and insulin detemir (Levemir®) were gathered from the past 20 years (except for receptor binding studies). A total of 50 reports were retrieved, with great heterogeneity among study methodology. However, various differences in bioactivity compared to human insulin were obvious (e.g. differences in effects on metabolism, mitogenesis, apoptosis, intracellular signalling, thrombocyte function, protein degradation). Whether or not these differences have clinical bearings (and among which patient populations) remains to be determined.

Insulin glargine use and short-term incidence of malignancies - a three-year population-based observation

AIMS/HYPOTHESIS

To further investigate the association of cancer occurrence with the use of insulin glargine.

METHODS

We followed 114 838 individuals using insulin between 1 July and 31 December 2005. From 1 January 2006 to 31 December 2008, we noted the occurrence of malignancies (cohort I). Insulin users between 1 July and 31 December 2006 were followed for the occurrence of malignancies in 2007 and 2008 (cohort II). Users of insulin during three consecutive six-month periods from 1 July 2005 to 31 December 2006 were followed for the occurrence of malignancies in 2007 and 2008 (cohort III). The Prescribed Drug Register, the Cancer Register, and the Causes of Death Register were used to obtain information on targeted person-time and outcome. We retrieved variables reflecting potential confounding factors from the Swedish National Diabetes Register, the Prescribed Drug Register, the Patient Register, the Medical Birth Register and the National Education Register. With Poisson regression we evaluated the association between insulin use and malignancy outcome with adjustment for confounders.

RESULTS

The adjusted incidence rate ratio (and 95% confidence interval) for women who used insulin glargine alone compared with those who used other types of insulin, was 1.60 (1.10-2.32) for breast cancer but included 1.0 for malignancy outcomes other than breast cancer for men and women when analyzing cohort I with follow-up in 2006-2008. For cohort II and III the corresponding incidence rate ratios were 1.38 (0.87-2.18), and 0.87 (0.41-1.85), respectively.

CONCLUSION/INTERPRETATION

We do not see an increased risk during 2008 for breast cancer in the insulin glargine group. We need data for additional years before we can state with reasonable certainty that the increase in breast cancer incidence that we observed in Sweden in 2006 and 2007 was due to a random fluctuation or whether there is an association with the use of insulin glargine.

Controversies in the use of insulin analogues

INTRODUCTION

In recent years, insulin analogues have been developed in order to improve the pharmacological parameters of insulin and to better mimic endogenous insulin output. Given that some of the modifications introduced into insulin analogues are located in a domain involved in a potential interaction with the insulin-like growth factor-I receptor (IGF-IR), it has been postulated that certain analogues may display IGF-I-like activities.

AREAS COVERED

We review the recent literature investigating the risk of malignant neoplasms and mortality in diabetic patients treated either with human insulin or with one of three insulin analogues (lispro, aspart, and glargine). We examine how critical analyses are consistent with the notion that the use of insulin glargine is associated with a possible increased risk of tumors in humans.

EXPERT OPINION

The introduction of insulin analogues has had a major impact in diabetes care. However, the benefit of some of these new insulins for the patient has yet to be demonstrated. Furthermore, research is needed to clarify whether insulin glargine is more strongly associated with cancer risk compared with other insulins.

Glucose metabolism disorders and the risk of cancer

Diabetes and cancer are diseases which take the size of an epidemic spread across the globe. Those diseases are influenced by many factors, both genetic and environmental. Precise knowledge of the complex relationships and interactions between these two conditions is of great importance for their prevention and treatment. Many epidemiological studies have shown that certain types of cancer, especially gastrointestinal cancers (pancreas, liver, colon) and also the urinary and reproductive system cancers in women are more common in patients with diabetes or related metabolic disorders. There are also studies showing the inverse relationship between diabetes and cancer, or the lack of it, but they are less numerous and relate mainly to prostate cancer or squamous cell carcinoma of the esophagus. Epidemiological studies, however, do not say anything about the mechanisms of these dependencies. For this purpose, molecular research is needed on the metabolism of cells (including tumor cells) and on metabolic dysfunctions that arise due to changes in the cell environment taking place in the sick, as well as in the intensely treated human organism.

The IGF system

The insulin-like growth factor (IGF) system plays essential role in the regulation of cell growth, proliferation and survival and affects nearly every organ system in the body. IGF-I, which has a high structural similarity to insulin, exerts growth-promoting effects, influences glucose metabolism and has neuroprotective and cardioprotective effects, partly because of its cell-proliferative and antiapoptotic properties. Aberrations in the IGF system may associate with various pathological conditions, including cancer. Insulin and its synthetic analogs are known to possess IGF-IR binding affinity, and concern has been raised about their mitogenic potential in humans. The present review summarizes the main aspects of the IGF system biology and the interactions among IGF-I, insulin, insulin analogs and their receptors.

Doses of insulin and its analogues and cancer occurrence in insulin-treated type 2 diabetic patients

OBJECTIVE

Recent epidemiological studies suggested that some insulin analogues could be associated with increased risk of cancer. The present study is aimed at assessing the long-term association of different insulin analogues with cancer incidence.

RESEARCH DESIGN AND METHODS

A nested case-control study dataset was generated from the cohort study dataset (n = 1,340 insulin-treated diabetic outpatients) by sampling control subjects from the risk sets. For each case subject, the control subjects (up to five) were chosen randomly from those members of the cohort who are at risk for the same follow-up time of the case subject. Five-year age classes, sex, and BMI classes (<18.5, 18.5-24.9, 25-29.9, and >or=30 kg/m(2)) were considered as additional categorical matching variables.

RESULTS

During a median follow-up of 75.9 months (interquartile range 27.4-133.7), 112 case subjects of incident cancer were compared with 370 matched control subjects. A significantly higher mean daily dose of glargine was observed in case subjects than in control subjects (0.24 IU/kg/day [0.10-0.39] versus 0.16 IU/kg/day [0.12-0.24], P = 0.036). Incident cancer was associated with a dose of glargine >or=0.3 IU/kg/day even after adjusting for Charlson comorbidity score, other types of insulin administration, and metformin exposure (odds ratio 5.43 [95% CI 2.18-13.53], P < 0.001). No association between incident cancer and insulin doses was found for human insulin or other analogues.

CONCLUSIONS

The possibility of association between cancer and higher glargine doses suggests that dosages should always be considered when assessing the possible association of insulin and its analogues with cancer.