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HbA1C and cancer risk in patients with type 2 diabetes--a nationwide population-based prospective cohort study in Sweden.

Miao Jonasson J, Cederholm J, Eliasson B, Zethelius B, Eeg-Olofsson K, Gudbjörnsdottir S - PLoS ONE (2012)

Bottom Line: The underlying mechanisms remain unclear.Hyperglycemia might be one risk factor.This is a cohort study on 25,476 patients with type 2 diabetes registered in the Swedish National Diabetes Register from 1997-1999 and followed until 2009.

View Article: PubMed Central - PubMed

Affiliation: Center of Registers in Region Västra Götaland, Gothenburg, Sweden. junmei.miao.jonasson@gmail.com

ABSTRACT

Background: Diabetes is associated with increased cancer risk. The underlying mechanisms remain unclear. Hyperglycemia might be one risk factor. HbA1c is an indicator of the blood glucose level over the latest 1 to 3 months. This study aimed to investigate association between HbA1c level and cancer risks in patients with type 2 diabetes based on real life situations.

Methods: This is a cohort study on 25,476 patients with type 2 diabetes registered in the Swedish National Diabetes Register from 1997-1999 and followed until 2009. Follow-up for cancer was accomplished through register linkage. We calculated incidences of and hazard ratios (HR) for cancer in groups categorized by HbA1c ≤ 58 mmol/mol (7.5%) versus >58 mmol/mol, by quartiles of HbA1c, and by HbA1c continuously at Cox regression, with covariance adjustment for age, sex, diabetes duration, smoking and insulin treatment, or adjusting with a propensity score.

Results: Comparing HbA1c >58 mmol/mol with ≤ 58 mmol/mol, adjusted HR for all cancer was 1.02 [95% CI 0.95-1.10] using baseline HbA1c, and 1.04 [95% CI 0.97-1.12] using updated mean HbA1c, and HRs were all non-significant for specific cancers of gastrointestinal, kidney and urinary organs, respiratory organs, female genital organs, breast or prostate. Similarly, no increased risks of all cancer or the specific types of cancer were found with higher quartiles of baseline or updated mean HbA1c, compared to the lowest quartile. HR for all cancer was 1.01 [0.98-1.04] per 1%-unit increase in HbA1c used as a continuous variable, with non-significant HRs also for the specific types of cancer per unit increase in HbA1c.

Conclusions: In this study there were no associations between HbA1c and risks for all cancers or specific types of cancer in patients with type 2 diabetes.

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Related in: MedlinePlus

The flow chart presenting the compilation of the study cohort.
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pone-0038784-g001: The flow chart presenting the compilation of the study cohort.

Mentions: This is a prospective cohort study based on Swedish Registers: the National Diabetes Register, the Cancer Register and the Causes of Death Register. More details about these registers have been described in a previous publication [14]. The study cohort, all patients with type 2 diabetes, was selected from the Swedish National Diabetes Register, with baseline years 1997–1999. The cohort selected for the current study is based upon registry entries in the Swedish National Diabetes Register from 1997–1999, which are completely different from those used for the study on insulin glargine and cancer risk, where the cohort was selected based on registry entries in the Swedish Prescribed Drug Register in 2005 [14]. Outcomes during follow-up of the study cohort were obtained through linkage to the Cancer Register and the Causes of Death Register, with use of the Swedish personal identity number, a unique identifier assigned to every resident in Sweden and allowing linkage between different registers [14]. Figure 1 presents the compilation of the study cohort in the form of a flow chart.


HbA1C and cancer risk in patients with type 2 diabetes--a nationwide population-based prospective cohort study in Sweden.

Miao Jonasson J, Cederholm J, Eliasson B, Zethelius B, Eeg-Olofsson K, Gudbjörnsdottir S - PLoS ONE (2012)

The flow chart presenting the compilation of the study cohort.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3375298&req=5

pone-0038784-g001: The flow chart presenting the compilation of the study cohort.
Mentions: This is a prospective cohort study based on Swedish Registers: the National Diabetes Register, the Cancer Register and the Causes of Death Register. More details about these registers have been described in a previous publication [14]. The study cohort, all patients with type 2 diabetes, was selected from the Swedish National Diabetes Register, with baseline years 1997–1999. The cohort selected for the current study is based upon registry entries in the Swedish National Diabetes Register from 1997–1999, which are completely different from those used for the study on insulin glargine and cancer risk, where the cohort was selected based on registry entries in the Swedish Prescribed Drug Register in 2005 [14]. Outcomes during follow-up of the study cohort were obtained through linkage to the Cancer Register and the Causes of Death Register, with use of the Swedish personal identity number, a unique identifier assigned to every resident in Sweden and allowing linkage between different registers [14]. Figure 1 presents the compilation of the study cohort in the form of a flow chart.

Bottom Line: The underlying mechanisms remain unclear.Hyperglycemia might be one risk factor.This is a cohort study on 25,476 patients with type 2 diabetes registered in the Swedish National Diabetes Register from 1997-1999 and followed until 2009.

View Article: PubMed Central - PubMed

Affiliation: Center of Registers in Region Västra Götaland, Gothenburg, Sweden. junmei.miao.jonasson@gmail.com

ABSTRACT

Background: Diabetes is associated with increased cancer risk. The underlying mechanisms remain unclear. Hyperglycemia might be one risk factor. HbA1c is an indicator of the blood glucose level over the latest 1 to 3 months. This study aimed to investigate association between HbA1c level and cancer risks in patients with type 2 diabetes based on real life situations.

Methods: This is a cohort study on 25,476 patients with type 2 diabetes registered in the Swedish National Diabetes Register from 1997-1999 and followed until 2009. Follow-up for cancer was accomplished through register linkage. We calculated incidences of and hazard ratios (HR) for cancer in groups categorized by HbA1c ≤ 58 mmol/mol (7.5%) versus >58 mmol/mol, by quartiles of HbA1c, and by HbA1c continuously at Cox regression, with covariance adjustment for age, sex, diabetes duration, smoking and insulin treatment, or adjusting with a propensity score.

Results: Comparing HbA1c >58 mmol/mol with ≤ 58 mmol/mol, adjusted HR for all cancer was 1.02 [95% CI 0.95-1.10] using baseline HbA1c, and 1.04 [95% CI 0.97-1.12] using updated mean HbA1c, and HRs were all non-significant for specific cancers of gastrointestinal, kidney and urinary organs, respiratory organs, female genital organs, breast or prostate. Similarly, no increased risks of all cancer or the specific types of cancer were found with higher quartiles of baseline or updated mean HbA1c, compared to the lowest quartile. HR for all cancer was 1.01 [0.98-1.04] per 1%-unit increase in HbA1c used as a continuous variable, with non-significant HRs also for the specific types of cancer per unit increase in HbA1c.

Conclusions: In this study there were no associations between HbA1c and risks for all cancers or specific types of cancer in patients with type 2 diabetes.

Show MeSH
Related in: MedlinePlus