Factors Associated with Cancer- and Non-Cancer-Related Deaths among Taiwanese Patients with Diabetes after 17 Years of Follow-Up

OBJECTIVE

A previous 12-year follow-up of a large diabetes cohort in Taiwan suggested a survival advantage in the patients with obesity. The present study further investigated additional determinants for cancer and non-cancer death in the cohort after a follow-up of 17 years.

METHODS

A cohort of 92546 diabetes patients recruited since 1995 was followed for vital status by matching the National Death Certificate Database until 2011. Cox regression estimated the hazard ratios for the following variables: age at baseline, sex, diabetes type, screen-detected diabetes (diabetes diagnosed accidentally through epidemiological screening programs or during visits to medical settings without a history of diabetes), diabetes duration, body mass index, insulin use, hypertension, smoking, and living region. Fasting glucose and history of dyslipidemia were available for additional adjustment in a subcohort of the patients (n = 14559).

RESULTS

A total of 40229 diabetes patients (43.5% of the cohort) died during follow-up and 10.9% died under the age of 60. Insulin use and smoking significantly predicted cancer and non-cancer death. The adjusted hazard ratio (95% confidence interval) associated with insulin use was 1.161 (1.052-1.281) for cancer death and 1.469 (1.413-1.526) for non-cancer death. Screen-detected diabetes and body mass index were consistently associated with a lower risk, but diabetes duration a higher risk, for non-cancer death, with adjusted hazard ratio of 0.683 (0.666-0.702), 0.955 (0.951-0.958) and 1.018 (1.017-1.020), respectively. Diabetes type had a null association disregarding the causes of death and living in rural areas was significantly associated with a higher mortality from non-cancer death. Hypertension, fasting glucose and dyslipidemia showed differential impacts on cancer and non-cancer death, and were significantly predictive for non-cancer death.

CONCLUSIONS

Screen-detected diabetes and a higher body mass index provide a survival advantage, especially for non-cancer death. However, insulin use is associated with a significantly higher risk of either cancer or non-cancer death.

Metformin reduces gastric cancer risk in patients with type 2 diabetes mellitus

This retrospective cohort study investigated whether metformin may reduce gastric cancer risk by using the reimbursement databases of the Taiwan's National Health Insurance. Patients with type 2 diabetes diagnosed during 1999-2005 and newly treated with metformin (n=287971, "ever users of metformin") or other antidiabetic drugs (n=16217, "never users of metformin") were followed until December 31, 2011. The effect of metformin (for ever versus never users, and for tertiles of cumulative duration of therapy) was estimated by Cox regression incorporated with the inverse probability of treatment weighting using propensity score. Results showed that the respective numbers of incident gastric cancer in ever and never users were 759 (0.26%) and 89 (0.55%), with respective incidences of 55.26 and 122.53 per 100,000 person-years. The overall hazard ratio (95% confidence intervals) of 0.448 (0.359-0.558) suggested a significantly lower risk among ever users. In tertile analyses, hazard ratios (95% confidence intervals) for the first (＜21.47 months), second (21.47-45.97 months) and third (＞45.97 months) tertile of cumulative duration was 0.973 (0.773-1.224), 0.422 (0.331-0.537) and 0.120 (0.090-0.161), respectively, while compared to never users. In conclusion, metformin significantly reduces gastric cancer risk, especially when the cumulative duration is more than approximately 2 years.

Sitagliptin and pancreatic cancer risk in patients with type 2 diabetes

BACKGROUND

The risk of pancreatic cancer associated with incretin-based therapies is controversial.

METHODS

This study retrospectively analysed the National Health Insurance database including patients with newly diagnosed type 2 diabetes mellitus at an age ≥ 25 years between 1999 and 2010. A total of 71 137 ever users of sitagliptin and 933 046 never users were followed for pancreatic cancer until 31 December 2011. A time-dependent approach was used to calculate incidence and estimate hazard ratios adjusted for propensity score using Cox regression.

RESULTS

During follow-up, 83 ever users and 3658 never users developed pancreatic cancer, representing an incidence of 73·6 and 55·0 per 100 000 person-years, respectively. The adjusted hazard ratio (95% confidence intervals) for ever versus never users was 1·40 (1·13-1·75). The respective adjusted hazard ratio for the first, second and third tertile of cumulative dose < 14 700, 14 700-33 700 and > 33 700 mg was 1·83 (1·28-2·62), 1·97 (1·41-2·76) and 0·72 (0·45-1·15). For average daily dose of < 50, 50-99·9 and ≥ 100 mg, the respective hazard ratio was 3·10 (1·17-8·26), 1·01 (0·63-1·61) and 1·53 (1·18-1·97).

CONCLUSIONS

Sitagliptin is significantly associated with a higher risk of pancreatic cancer, especially when the cumulative dose is < 33 700 mg. The risk diminished in users with a higher cumulative dose. The daily dose of sitagliptin should better be kept < 100 mg, and its use should be reconsidered in patients who suffer from severe renal impairment and thus a daily dose of < 50 mg is always recommended. Future studies are required to confirm the findings with more appropriate adjustment for smoking.

Electro-optically spectrum tailorable intracavity optical parametric oscillator

We report a unique, pulsed intracavity optical parametric oscillator (IOPO) whose output spectrum is electro-optically (EO) tailorable based on an aperiodically poled lithium niobate (APPLN) working simultaneously as an optical parametric gain medium and an active gain spectrum filter in the system. We have successfully obtained from the IOPO the emission of single to multiple narrow-line signal spectral peaks in a near-infrared (1531 nm) band simply by electro-optic control. The power spectral density of the EO tailored signal can be enhanced by up to 10 times over the original (nontailored) signal.

Type 2 Diabetes Mellitus and Kidney Cancer Risk: A Retrospective Cohort Analysis of the National Health Insurance

Purpose

To evaluate the association between incidence of any kidney cancer and type 2 diabetes mellitus.

Methods

A random sample of 1,000,000 subjects covered by the National Health Insurance was recruited. A total of 998728 people (115655 diabetes and 883073 non-diabetes) without kidney cancer at recruitment were followed from 2003 to 2005. The cumulative incidence of kidney cancer from 2003 to 2005 in diabetic patients and non-diabetic people in all ages and in age <40, 40–64, 65–74 and ≥75 years were calculated in the diabetic patients and the non-diabetic people, respectively. Logistic regression was used to estimate the odds ratios comparing diabetic patients to non-diabetic people in the respective age groups. Multivariable-adjusted odds ratios for kidney cancer with regards to diabetes status and diabetes duration (as a continuous variable or categorized into subgroups of non-diabetes, diabetes duration <1 year, 1–2.9 years, 3–4.9 years and ≥5 years) were estimated after multivariable adjustment. The multivariable-adjusted odds ratios for all baseline variables were also estimated for diabetic patients and non-diabetic people, respectively.

Results

The 3-year cumulative incidence of kidney cancer in the diabetic patients and the non-diabetic people was 166.9 and 33.1 per 100,000 person-years, respectively. The incidence increased with regards to increasing age in both the diabetic patients and the non-diabetic people, but a higher risk of kidney cancer for the diabetic patients compared to the non-diabetic people was consistently observed in different age groups. After multivariable adjustment, the odds ratio for diabetic patients versus non-diabetic people was 1.7 (95% confidence interval: 1.3–2.1, P<0.01). While compared to the non-diabetic people, the odds ratio (95% confidence interval) for diabetes duration <1, 1–2.9 years, 3–4.9 years and ≥5 years was 1.5 (0.8–2.7), 1.6 (1.0–2.4), 1.6 (1.1–2.4) and 1.7 (1.3–2.3), respectively (P-trend <0.01). Analyses conducted in the diabetic patients and the non-diabetic people, respectively, consistently showed age, nephropathy and end-stage renal disease as significant risk factors of kidney cancer. Additionally, living in metropolitan Taipei region might also be associated with a higher risk of kidney cancer in the non-diabetic people, indicating a potential link between kidney cancer and some factors related to urbanization.

Conclusions

Patients with type 2 diabetes mellitus have a significantly higher risk of kidney cancer.

Prolonged use of human insulin increases breast cancer risk in Taiwanese women with type 2 diabetes

Background

Human insulin is commonly used to treat hyperglycemia in patients with diabetes, but its potential link with female breast cancer is under debate. This study investigated whether human insulin use might be associated with breast cancer risk in Taiwanese women with type 2 diabetes.

Methods

The reimbursement databases of all Taiwanese diabetic patients from 1996 to 2009 were retrieved from the National Health Insurance. An entry date was set at 1 January 2004 and a total of 482,033 women with type 2 diabetes were followed up for breast cancer incidence until the end of 2009. Incidences for ever-users, never-users and subgroups of human insulin exposure (using tertile cutoffs of time since starting insulin, cumulative dose and cumulative duration of insulin) were calculated and the adjusted hazard ratios were estimated by Cox regression. The potential risk modification by concomitant treatment with metformin, statin and angiotensin converting enzyme inhibitor/angiotensin receptor blocker (ACEI/ARB) was also evaluated.

Results

There were 59,798 ever-users and 422,235 never-users of human insulin, with respective numbers of incident breast cancer of 559 (0.93 %) and 4,711 (1.12 %), and respective incidence of 207.9 and 215.1 per 100,000 person-years. The overall adjusted hazard ratio (95 % confidence interval) did not show a significant association with insulin [1.033 (0.936-1.139)]. However, patients in the third tertiles of dose–response parameters might show a significantly higher risk of breast cancer while compared to never-users: 1.185 (1.026-1.368), 1.260 (1.096-1.450) and 1.257 (1.094-1.446) for ≥67 months for time since starting insulin, ≥39,000 units for cumulative dose of insulin, and ≥21.8 months for cumulative duration of insulin, respectively. Additional analyses suggested that the breast cancer risk associated with human insulin use might be beneficially modified by concomitant use of metformin, statin and ACEI/ARB.

Conclusions

This study discloses a significantly higher risk of breast cancer associated with prolonged use of human insulin. The increased risk of breast cancer associated with human insulin use may be modified by medications such as metformin, statin and ACEI/ARB.

Human insulin to increase breast cancer risk in Taiwanese women with type 2 diabetes

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Background: To investigate whether human insulin use may be associated with risk of breast cancer in Taiwanese women with type 2 diabetes. Methods: The reimbursement databases of all Taiwanese diabetic patients from 1996 to 2009 were retrieved from the National Health Insurance. An entry date was set at 1 January 2004 and a total of 482,065 women with type 2 diabetes were followed up for breast cancer incidence until the end of 2009. Incidences for ever-users, never-users and subgroups of human insulin exposure (using tertile cutoffs of time since starting insulin, cumulative dose and cumulative duration of insulin) were calculated and the multivariable-adjusted hazard ratios were estimated by Cox regression. Results: There were 59,830 ever-users and 422,235 never-users, with respective numbers of incident breast cancer of 559 (0.93%) and 4,711 (1.12%), and respective incidence of 207.7 and 215.1 per 100,000 person-years. The overall adjusted hazard ratios (95% confidence intervals) did not show a significant association with insulin [1.098 (0.994-1.212)]. However, significant trends for the different categories of the dose-responsive parameters were observed. Patients in the third tertiles consistently showed a significantly higher risk of breast cancer while compared to never-users: 1.263 (1.093-1.458), 1.339 (1.164-1.540) and 1.331 (1.158-1.531) for ≥ 67 months for time since starting insulin, ≥ 39,000 units for cumulative dose of insulin, and ≥ 21.8 months for cumulative duration of insulin, respectively. Conclusions: This study discloses a significantly higher risk of breast cancer associated with the use of human insulin, demonstrating a significant dose-responsive relationship.

Metformin reduces ovarian cancer risk in Taiwanese women with type 2 diabetes mellitus

BACKGROUND

Whether metformin therapy affects ovarian cancer risk in Asian patients with type 2 diabetes mellitus has not been investigated.

METHODS

Data analysis was performed in 2014. The reimbursement databases of Taiwanese female patients with a new diagnosis of type 2 diabetes mellitus between 1998 and 2002 (n = 479,475) were retrieved from the National Health Insurance for follow-up of ovarian cancer until the end of 2009. Metformin was treated as a time-dependent variable; and of these patients, 286,106 were never-users, and 193,369 were ever-users. A time-dependent approach was used to calculate ovarian cancer incidence and estimate hazard ratios by Cox regression for never-users (as referent group), ever-users and subgroups of metformin exposure (tertiles of cumulative duration and cumulative dose).

RESULTS

During follow-up, 601 metformin ever-users and 2600 never-users developed ovarian cancer, representing an incidence of 49.4 and 146.4 per 100,000 person-years, respectively. The overall fully adjusted hazard ratio (95% confidence intervals) for ever-users versus never-users was 0.658 (0.593-0.730). The fully adjusted hazard ratios for the first, second and third tertiles of cumulative duration of metformin therapy were 1.169 (1.019-1.341), 0.761 (0.644-0.898) and 0.276 (0.225-0.340), respectively (p trend < 0.01) and 1.220 (1.067-1.395), 0.610 (0.513-0.725) and 0.305 (0.248-0.374), respectively (p trend < 0.01), for a cumulative dose of metformin. In additional analyses, sulfonylureas but not the other antidiabetic drugs were associated with a reduced risk of ovarian cancer.

CONCLUSIONS

Metformin use is associated with a decreased risk of ovarian cancer.

Rosiglitazone may reduce non-melanoma skin cancer risk in Taiwanese

Background

Whether rosiglitazone may affect the risk of non-melanoma skin cancer (NMSC) has not been investigated.

Methods

The reimbursement databases of all Taiwanese diabetic patients from 1996 to 2009 were retrieved from the National Health Insurance. An entry date was set at 1 January 2006 and a total of 886418 patients with type 2 diabetes were followed up for NMSC incidence until the end of 2009. Incidences for ever-users, never-users and subgroups of rosiglitazone exposure (using tertile cutoffs of duration of therapy and cumulative dose) were calculated and hazard ratios estimated by Cox regression. Additional models were created as sensitivity analyses.

Results

There were 103097 ever-users and 783321 never-users, respective numbers of incident NMSC 250 (0.24%) and 2084 (0.27%), and respective incidence 68.90 and 76.77 per 100000 person-years. Although the overall hazard ratio was not significant in the unadjusted, age-sex-adjusted or fully adjusted model, the risk was significantly lower in the third tertile of duration of therapy and cumulative dose, with significant P for trends. The fully adjusted hazard ratio (95% confidence interval) for a duration of therapy >13.77 months and a cumulative dose of >1752 mg was 0.723 (0.566, 0.923) and 0.783 (0.618, 0.993), respectively. The findings were supported by various sensitivity analyses.

Conclusions

Rosiglitazone may reduce the risk of NMSC, but further confirmation is required.

Sitagliptin increases acute pancreatitis risk within 2 years of its initiation: A retrospective cohort analysis of the National Health Insurance database in Taiwan

PURPOSE

To evaluate the risk of acute pancreatitis hospitalization with sitagliptin use in patients with type 2 diabetes mellitus (T2DM).

METHODS

This retrospective cohort analysis included newly diagnosed T2DM with onset age ≥25 years between 1999 and 2010 from the National Health Insurance database. Ever users (n = 89,800) and never users (n = 449,000) of sitagliptin were followed until end of 2011. A time-dependent approach was used to calculate event incidence and estimate hazard ratios adjusted for propensity score.

RESULTS

During follow-up, 261 ever users and 5,840 never users were hospitalized for acute pancreatitis (respective incidence, 224.0 and 168.4 per 100,000 person-years), with adjusted hazard ratio of 1.59 (95% CI 1.40-1.81). The respective hazard ratio for the first, second, and third tertile of time since starting sitagliptin <9.5, 9.5-21.0, and >21.0 months was 8.10 (6.80-9.65), 1.70 (1.38-2.11), and 0.41 (0.30-0.56); 3.26 (2.67-3.98), 1.86 (1.52-2.27), and 0.76 (0.59-0.98) for cumulative duration <3.7, 3.7-10.3, and >10.3 months; and 3.21 (2.65-3.90), 1.89 (1.54-2.32), and 0.73 (0.57-0.95) for cumulative dose <9,000, 9,000-28,000, and >28,000 mg.

CONCLUSIONS

Sitagliptin is associated with a higher risk of acute pancreatitis within the first 2 years of its initiation. The risk diminishes thereafter, probably due to the depletion of susceptible patients.

An updated review on cancer risk associated with incretin mimetics and enhancers

Incretin-based therapies, including the use of incretin mimetics of glucagon-like peptide-1 receptor (GLP-1R) agonists and incretin enhancers of dipeptidyl-peptidase 4 (DPP-4) inhibitors, are widely used by clinicians for glucose lowering in patients with type 2 diabetes mellitus. These agents have benefits of a lower risk of hypoglycemia, being neutral for body weight for DPP-4 inhibitors and having a potential for weight reduction with GLP-1R agonists. They may also have a neutral or beneficial cardiovascular effect. Despite these benefits, an increased risk of cancer (especially pancreatic cancer and thyroid cancer) associated with incretin-based therapies has been reported. In this article, we reviewed related literature of experimental animal and observational human studies, clinical trials, and meta-analyses published until December 15, 2014. Current studies suggested a probable role of GLP-1R activation on the development of pancreatic cancer and thyroid cancer in rodents, but such an effect in humans is not remarkable due to the lower or lack of expression of GLP-1R on human pancreatic ductal cells and thyroid tissues. Findings in human studies are controversial and inconclusive. In the analyses of the US Food and Drug Administration adverse events reporting system, a significantly higher risk of pancreatic cancer was observed for GLP-1R agonists and DPP-4 inhibitors, but a significantly higher risk of thyroid cancer was only observed for GLP-1R agonists. Such a higher risk of pancreatic cancer or thyroid cancer could not be similarly demonstrated in other human observational studies or analyses of data from clinical trials. With regards to cancers other than pancreatic cancer and thyroid cancer, available studies supported a neutral association in humans. Some preliminary studies even suggested a potentially beneficial effect on the development of other cancers with the use of incretins. Based on current evidence, continuous monitoring of the cancer issues related to incretin-based therapies is required, even though the benefits may outweigh the potential cancer risk in the general patients with type 2 diabetes mellitus.

Use of Insulin and Mortality from Breast Cancer among Taiwanese Women with Diabetes

Background. To evaluate whether insulin use was predictive for mortality from breast cancer in Taiwanese women with diabetes mellitus. Methods. A total of 48,880 diabetic women were followed up to determine the mortality from breast cancer during 1995-2006. Cox models were used, considering the following independent variables: age, sex, diabetes type, diabetes duration, body mass index, smoking, insulin use, and area of residence. Insulin use was also considered for its duration of use at cutoffs of 3 years and 5 years. Results. Age was a significant predictor in all analyses. The multivariable-adjusted hazard ratio (95% confidence interval, P value) for insulin use without considering the duration of use was not statistically significant (1.339 [0.782-2.293, P = 0.2878]). Compared with nonusers, insulin users showed the following adjusted hazard ratios for insulin use <3 years, ≥3 years, <5 years, and ≥5 years: 0.567 (0.179-1.791, P = 0.3333), 2.006 (1.102-3.653, P = 0.0228), 1.045 (0.505-2.162, P = 0.9048), and 1.899 (0.934-3.860, P = 0.0763). Conclusions. Insulin use (mainly human insulin) for ≥3 years may be associated with a higher risk of breast cancer mortality.

Metformin reduces thyroid cancer risk in Taiwanese patients with type 2 diabetes

Background

Whether metformin may affect thyroid cancer risk has not been studied. This study investigated the association between metformin use and thyroid cancer risk in Taiwanese patients with type 2 diabetes mellitus.

Methods

The reimbursement databases of all diabetic patients from 1996 to 2009 were retrieved from the National Health Insurance. An entry date was set at 1 January 2006 and 1,414,723 patients with type 2 diabetes were followed for thyroid cancer incidence until the end of 2009. Incidences for ever-users, never-users and subgroups of metformin exposure using tertile cutoffs for cumulative duration of therapy and cumulative dose were calculated and adjusted hazard ratios were estimated by Cox regression. Additional sensitivity analyses were conducted.

Results

There were 795,321 ever-users and 619,402 never-users, with respective numbers of incident thyroid cancer of 683 (0.09%) and 1,614 (0.26%), and respective incidence of 24.09 and 87.33 per 100,000 person-years. The overall fully adjusted hazard ratio (95% confidence interval) was 0.683 (0.598–0.780), and all categories of the dose-response parameters showed significantly lower risk with P-trends <0.0001. The protective effect of metformin on thyroid cancer incidence was also supported by sensitivity analyses, disregarding age (<50 or ≥50 years) and sex; and was not affected by excluding users of insulin, sulfonylurea, and insulin and/or sulfonylurea respectively, by previous diagnosis of other cancers or by potential detection examinations that might lead to differential diagnosis of thyroid cancer.

Conclusions

This study provides evidence for the first time that metformin use in patients with type 2 diabetes may reduce the risk of thyroid cancer.

Diabetes and breast cancer in Taiwanese women: a detection bias?

PURPOSE

To evaluate whether diabetes is a risk factor for breast cancer considering confounders and potential detection examinations.

METHODS

National Health Insurance data on 501,747 women without breast cancer were retrieved. Three-year cumulative incidence (2003-2005) and risk ratios (RRs) between diabetic and nondiabetic women were calculated. Potential detection examinations were compared between diabetic and nondiabetic women by chi-square test. Odds ratios (ORs) were estimated by logistic regression for diabetes status/duration with and without adjustment for potential detection examinations and confounders.

RESULTS

The crude RR (95% confidence interval [CI]) for all ages, and age groups < 50, 50-64 and ≥ 65 years, was 2·62 (2·31-2·91), 2·69 (2·11-3·44), 1·39 (1·15-1·68) and 1·37 (1·03-1·84), respectively. Patients with diabetes more frequently received potential detection examinations than nondiabetes (17·5% vs. 7·4%, P-value < 0·001). The unadjusted OR (95% CI) for breast cancer for diabetes status (yes vs. no) was 2·63 (2·31-2·98) and was significant for any diabetes duration. The OR for diabetes status was 1·81 (95% CI: 1·59-2·06) after adjustment for potential detection examinations. In models adjusted for potential detection examinations, age, living region, occupation, comorbidities and used medications, OR for diabetes status attenuated to 1·13 (95% CI 0·96-1·32, P-value = 0·14) and none was significant for any diabetes duration. Potential detection examinations were associated with a fivefold to sevenfold higher risk in various models, indicating a strong impact of detection bias.

CONCLUSIONS

An association between diabetes and breast cancer is observed, but this can be due to potential detection bias and confounders.

Effect of human insulin on breast cancer risk in Taiwanese women with type 2 diabetes

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Background: Whether human insulin may induce breast cancer is rarely studied. Methods: The reimbursement databases of all Taiwanese patients with diabetes from 1996 to 2009 were retrieved from the National Health Insurance. An entry date was set at January 1, 2004 and a total of 482,065 women with type 2 diabetes were followed up for breast-cancer incidence until the end of 2009. Incidences for ever-users, never-users, and subgroups of human insulin exposure (using tertile cutoffs of cumulative dose and cumulative duration of insulin) were calculated and the multivariable-adjusted hazard ratios were estimated by Cox regression. Results: There were 59,830 ever-users and 422,235 never-users, with respective numbers of incident breast cancer of 559 (0.93%) and 4,711 (1.12%), and respective incidence of 207.7 and 215.1 per 100,000 person-years. The overall adjusted hazard ratios (95% confidence intervals) did not show a significant association with insulin [1.098 (0.994-1.212)]. However, significant trends for the different categories of the dose-responsive parameters were observed. Patients in the third tertiles consistently showed a significantly higher risk of breast cancer compared to never-users: 1.339 (1.164-1.540) and 1.331 (1.158-1.531) for ≥ 39,000 units for cumulative dose of insulin, and ≥ 21.8 months for cumulative duration of insulin, respectively. Conclusions: This study discloses a significantly higher risk of breast cancer associated with the use of human insulin, demonstrating a significant dose-responsive relationship.

Treatment with human insulin does not increase thyroid cancer risk in patients with type 2 diabetes

BACKGROUND

Whether human insulin therapy may increase thyroid cancer risk in patients with type 2 diabetes mellitus (T2DM) has not been investigated.

MATERIALS AND METHODS

The reimbursement databases of all Taiwanese diabetic patients from 1996 to 2009 were retrieved from the Bureau of National Health Insurance. The entry date was set at 1 January 2004, and 968,384 patients with T2DM were followed up for thyroid cancer incidence until the end of 2009. Ever-users, never-users and subgroups of human insulin exposure (using tertile cut-offs of time since starting insulin, duration of therapy and cumulative dose) at entry date were calculated for thyroid cancer incidence. Insulin glargine was not marketed until after the entry date. Therefore, to exclude the potential contamination of insulin glargine, patients who happened to use insulin glargine were censored at the time of its initiation when calculating the period of follow-up. Hazard ratios were estimated by Cox regression.

RESULTS

There were 111,121 ever-users and 857,263 never-users of human insulin, with respective numbers of incident thyroid cancer of 118 (0·11%) and 1047 (0·12%), and respective incidences of 23·9 and 23·8 per 100,000 person-years. The overall hazard ratios (95% confidence intervals) did not show a significant association with human insulin in either the age-sex-adjusted or the fully adjusted model: 0·942 (0·778-1·141) and 1·096 (0·888-1·353), respectively. When categorized into tertiles of the dose-response parameters, none of the hazard ratios was significant.

CONCLUSIONS

This study does not support the role of human insulin therapy in increasing the risk of thyroid cancer in patients with T2DM.

Pioglitazone does not affect the risk of kidney cancer in patients with type 2 diabetes

OBJECTIVE

To investigate whether pioglitazone treatment of patients with type 2 diabetes mellitus was associated with an increased risk of kidney cancer.

METHODS

The reimbursement databases of all Taiwanese patients with type 2 diabetes who received oral anti-diabetic agents or insulin from 1996 to 2009 were retrieved from the National Health Insurance. An entry date was set at 1 January 2006, and a total of 1,093,675 patients with type 2 diabetes were followed up for kidney cancer incidence until the end of 2009. The incidences of kidney cancer among patients who had and had not received pioglitazone, as well as among subgroups of those treated with pioglitazone (sorted by time since starting pioglitazone, duration of treatment and cumulative dose) were calculated and hazard ratios (HRs) estimated by Cox regression analysis.

RESULTS

Of the 1,093,675 patients, 58,172 (5.3%) had and 1,035,503 (94.7%) had not received pioglitazone, with incident kidney cancer developing in 208 (0.36%) and 3304 (0.32%) patients, respectively, and a respective incidence of 97.7 and 90.5 per 100,000 person-years. Pioglitazone and kidney cancer were not significantly associated in unadjusted (HR 1.04; 95% confidence interval (CI), 0.90-1.20), age-sex-adjusted (HR 1.09; 95% CI, 0.95-1.25), and fully adjusted (HR 1.09; 95% CI, 0.94-1.26) models. None of the dose-response parameters showed a significant trend of risk association, with all P-trends >0.10.

CONCLUSIONS

Pioglitazone does not affect the risk of kidney cancer.

Diabetes but not insulin increases the risk of lung cancer: a Taiwanese population-based study

Background

The trend of lung cancer incidence in Taiwan is unknown, and the association between type 2 diabetes/insulin use and lung cancer is rarely studied.

Methods

The trends of lung cancer incidence in 1979–2007 in the Taiwanese general population were calculated. A random sample of 1,000,000 subjects covered by the National Health Insurance in 2005 was recruited. A total of 494,002 men and 502,948 women and without lung cancer were followed for the annual cumulative incidence of lung cancer in 2005, with calculation of the risk ratios between diabetic and non-diabetic subjects. Logistic regression estimated the adjusted odds ratios for risk factors.

Results

The trends increased significantly in both sexes (P<0.0001). The sex-specific annual cumulative incidence increased with age in either the diabetic or non-diabetic subjects, but the risk ratios attenuated with age. In logistic regressions, diabetes was associated with a significantly higher risk, with odds ratios (95% confidence interval) for diabetes duration <1, 1–3, 3–5 and ≥5 years versus non-diabetes of 2.189 (1.498-3.200), 1.420 (1.014-1.988), 1.545 (1.132-2.109), and 1.329 (1.063-1.660), respectively. Such an association was not related to a higher detection with chest X-ray examination. Insulin use and medications including oral anti-diabetic drugs, statin, fibrate, and anti-hypertensive agents were not significantly associated with lung cancer. Age, male sex, and chronic obstructive pulmonary disease were positively; but dyslipidemia, stroke and higher socioeconomic status were negatively associated with lung cancer.

Conclusions

Diabetes is significantly associated with a higher risk of lung cancer, but insulin use does not increase the risk.

Metformin may reduce bladder cancer risk in Taiwanese patients with type 2 diabetes

Whether metformin therapy affects bladder cancer risk in patients with type 2 diabetes mellitus (T2DM) has not been extensively investigated. The reimbursement databases of all Taiwanese patients with a new diagnosis of T2DM between 1998 and 2002 (n = 940,708) were retrieved from the National Health Insurance for follow-up of bladder cancer up to the end of 2009. Metformin was treated as a time-dependent variable, and of these patients, 532,519 were never-users and 408,189 were ever-users of metformin. A time-dependent approach was applied in the calculation of bladder cancer incidence and in the estimation of hazard ratios by Cox regression for ever-users, never-users, and subgroups of metformin exposure (using tertile cutoffs of cumulative duration of therapy and cumulative dose). During the study period, 1,847 (0.45%) metformin ever-users and 6,213 (1.17%) metformin never-users developed bladder cancer, representing an incidence of 72.03 and 189.22 per 100,000 person-years, respectively. The age-sex-adjusted and multivariable-adjusted hazard ratios (95% confidence intervals) for ever- versus never-users were 0.382 (0.360-0.405) and 0.600 (0.564-0.638), respectively. The multivariable-adjusted hazard ratios for the first, second, and third tertiles of cumulative duration of metformin therapy were 1.034 (0.954-1.120), 0.696 (0.632-0.766), and 0.258 (0.229-0.291), respectively (P trend <0.0001). Similarly, the multivariable-adjusted hazard ratios for the first, second, and third tertiles of cumulative dose of metformin were 0.997 (0.920-1.080), 0.615 (0.559-0.677), and 0.285 (0.253-0.321), respectively (P trend <0.0001). This study suggests that metformin use is associated with a decreased risk of bladder cancer in patients with T2DM.

Diabetes and gastric cancer: The potential links

This article reviews the epidemiological evidence linking diabetes and gastric cancer and discusses some of the potential mechanisms, confounders and biases in the evaluation of such an association. Findings from four meta-analyses published from 2011 to 2013 suggest a positive link, which may be more remarkable in females and in the Asian populations. Putative mechanisms may involve shared risk factors, hyperglycemia, Helicobacter pylori (H. pylori) infection, high salt intake, medications and comorbidities. Diabetes may increase the risk of gastric cancer through shared risk factors including obesity, insulin resistance, hyperinsulinemia and smoking. Hyperglycemia, even before the clinical diagnosis of diabetes, may predict gastric cancer in some epidemiological studies, which is supported by in vitro, and in vivo studies. Patients with diabetes may also have a higher risk of gastric cancer through the higher infection rate, lower eradication rate and higher reinfection rate of H. pylori. High salt intake can act synergistically with H. pylori infection in the induction of gastric cancer. Whether a higher risk of gastric cancer in patients with diabetes may be ascribed to a higher intake of salt due to the loss of taste sensation awaits further investigation. The use of medications such as insulin, metformin, sulfonylureas, aspirin, statins and antibiotics may also influence the risk of gastric cancer, but most of them have not been extensively studied. Comorbidities may affect the development of gastric cancer through the use of medications and changes in lifestyle, dietary intake, and the metabolism of drugs. Finally, a potential detection bias related to gastrointestinal symptoms more commonly seen in patients with diabetes and with multiple comorbidities should be pointed out. Taking into account the inconsistent findings and the potential confounders and detection bias in previous epidemiological studies, it is expected that there are still more to be explored for the clarification of the association between diabetes and gastric cancer.

Human insulin does not increase bladder cancer risk

Background

Whether human insulin can induce bladder cancer is rarely studied.

Methods

The reimbursement databases of all Taiwanese diabetic patients from 1996 to 2009 were retrieved from the National Health Insurance. An entry date was set at 1 January 2004 and a total of 785,234 patients with type 2 diabetes were followed up for bladder cancer incidence until the end of 2009. Users of pioglitazone were excluded and the period since the initiation of insulin glargine (marketed after the entry date in Taiwan) was not included in the calculation of follow-up. Incidences for ever-users, never-users and subgroups of human insulin exposure (using tertile cutoffs of time since starting insulin, duration of therapy and cumulative dose) were calculated and the hazard ratios were estimated by Cox regression.

Results

There were 87,940 ever-users and 697,294 never-users, with respective numbers of incident bladder cancer of 454 (0.52%) and 3,330 (0.48%), and respective incidence of 120.49 and 94.74 per 100,000 person-years. The overall hazard ratios (95% confidence intervals) indicated a significant association with insulin in the age-sex-adjusted models [1.238 (1.122–1.366)], but not in the model adjusted for all covariates [1.063 (0.951–1.187)]. There was also a significant trend for the hazard ratios for the different categories of the dose-response parameters in the age-sex-adjusted models, which became insignificant when all covariates were adjusted.

Conclusions

This study relieves the concern of a bladder cancer risk associated with human insulin. Appropriate adjustment for confounders is important in the evaluation of cancer risk associated with a medication.

A review on thiazolidinediones and bladder cancer in human studies

There is a concern of an increased risk of bladder cancer associated with the use of thiazolidinediones, a class of oral glucose-lowering drugs commonly used in patients with type 2 diabetes with a mechanism of improving insulin resistance. Human studies on related issues are reviewed, followed by a discussion on potential concerns on the causal inference in current studies. Pioglitazone and rosiglitazone are discussed separately, and findings from different geographical regions are presented. Randomized controlled trials designed for primarily answering such a cancer link are lacking, and evidence from clinical trials with available data for evaluating the association may not be informative. Observational studies have been reported with the use of population-based administrative databases, single-hospital records, drug adverse event reporting system, and case series collection. Meta-analysis has also been performed by six different groups of investigators. These studies showed a signal of higher risk of bladder cancer associated with pioglitazone, especially at a higher cumulative dose or after prolonged exposure; however, a weaker signal or null association is observed with rosiglitazone. In addition, there are some concerns on the causal inference, which may be related to the use of secondary databases, biases in sampling, differential detection, and confounding by indications. Lack of full control of smoking and potential biases related to study designs and statistical approaches such as prevalent user bias and immortal time bias may be major limitations in some studies. Overlapping populations and opposing conclusions in studies using the same databases may be of concern and weaken the reported conclusions of the studies. Because randomized controlled trials are expensive and unethical in providing an answer to this cancer issue, observational studies are expected to be the main source in providing an answer in the future. Furthermore, international comparison studies using well-designed and uniform methodology to clarify the risk in specific sexes, ethnicities, and other subgroups and to evaluate the interaction with other environmental risk factors or medications will be helpful to identify patients at risk.