Type 2 diabetes and insulin use associated with colorectal cancer in men, study finds

ScienceDaily (Oct. 18, 2010) ? There is an association between type 2 diabetes mellitus and colorectal cancer (CRC) among men, but not women, according to a new study in Gastroenterology, the official journal of the American Gastroenterological Association (AGA) Institute.

In 2000, the prevalence of type 2 diabetes was approximately 171 million worldwide, and 366 million people are projected to have the disease by 2030. Obesity, western-style diet and lack of physical activity are established risk factors for CRC. Hyperglycemia and hyperinsulinemia, which are especially pronounced during the early stages of type 2 diabetes, have been proposed as mediators for the association between CRC and type 2 diabetes. Although it is known that type 2 diabetes is associated with an increased risk of CRC, it is not clear if this association varies by gender or other factors.

"While our study supports an association of type 2 diabetes with colorectal cancer incidence among men, our results also suggest that insulin use is associated with a slight, but not a substantially increased, risk of colorectal cancer among men with type 2 diabetes," said Peter T. Campbell, PhD, of the American Cancer Society and lead author of this study. "Prevention strategies should emphasize adherence to guidelines intended for the general population such as smoking cessation, weight management, exercise and regular early detection exams."

In the final study of 73,312 men and 81,663 women, 1,567 men (227 with type 2 diabetes) and 1,242 women (108 with type 2 diabetes) were diagnosed with colon or rectal cancer by 2007. Among men, type 2 diabetes was associated with increased risk of incident CRC compared to not having type 2 diabetes. CRC risk was higher for those participants with type 2 diabetes regardless of whether or not they used insulin.

Among women, type 2 diabetes and insulin use were not associated with CRC risk. These findings support recent observations that the association may be more prominent in men than in women, and raise the possibility of a stronger association among individuals with a family history of CRC. This finding could have clinical relevance if confirmed by other large studies. The authors speculate that the lack of an association between type 2 diabetes and CRC risk among women might relate to improved glucose control among women with type 2 diabetes in recent years.

Participants were selected from the Cancer Prevention Study II Nutrition Cohort, a prospective study of cancer incidence. In 1992 or 1993, 184,194 adult participants completed a detailed, self-administered questionnaire. Follow-up questionnaires were sent in 1997 and every two years thereafter.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Gastroenterological Association, via EurekAlert!, a service of AAAS.

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Insulin resistance may be associated with stroke risk

ScienceDaily (Oct. 12, 2010) ? Insulin resistance, a condition in which insulin produced by the body becomes less effective in reducing blood glucose levels, appears to be associated with an increased risk of stroke in individuals without diabetes, according to a report in the October issue of Archives of Neurology, one of the JAMA/Archives journals.

Insulin resistance originates from several factors, including genetics, a sedentary lifestyle and obesity, according to background information in the article. The condition contributes significantly to the risk of cardiovascular disease, but whether it predicts ischemic stroke (interruption in blood flow to the brain due to a blood clot or another artery blockage) is still a matter of debate.

One widely used tool to estimate insulin sensitivity is the homeostasis model assessment (HOMA), calculated using fasting blood glucose and fasting insulin levels. Tatjana Rundek, M.D., Ph.D., of Miller School of Medicine, University of Miami, and colleagues assessed insulin resistance using HOMA for 1,509 non-diabetic participants in the Northern Manhattan Study, a study assessing stroke risk, incidence and prognosis in a multi-ethnic urban community. Participants were followed for an average of 8.5 years.

During the follow-up period, vascular events occurred in 180 participants, including 46 who had fatal or non-fatal ischemic strokes, 45 who had fatal or non-fatal heart attacks and 121 who died of vascular causes. Individuals in the top one-fourth (quartile) of HOMA index had an increased risk of stroke compared to those in the other three quartiles of the HOMA index. Adjusting for established cardiovascular risk factors -- including glucose level, obesity and metabolic syndrome -- did not diminish the association. The relationship between insulin resistance and the risk of first stroke was stronger in men than women but did not vary by racial or ethnic group.

Individuals in the top quarter of insulin resistance had a 45 percent greater risk of any type of vascular event. However, insulin resistance was not associated with heart attack or vascular death separately.

"There are several possible reasons for the stronger effect of insulin resistance on the risk of ischemic stroke than of myocardial infarction in the present study compared within other studies," the authors write. It may be because individuals with a history of heart attack were excluded from this study, or because factors associated with insulin resistance -- including high blood pressure, high triglyceride levels and low HDL or "good" cholesterol levels -- are more significant risk factors for stroke than for heart attack.

"These findings emphasize the need to better characterize individuals at increased risk for ischemic stroke and the potential role of primary preventive therapies targeted at insulin resistance," the authors conclude.

Editorial: Insulin Resistance Can Be Used to Refine Risk Stratification

"The implications of these findings are exciting if insulin resistance can be proven to be a causal risk factor for stroke (rather than a marker of increased risk) because insulin resistance cannot only be measured but also treated," write Graeme J. Hankey, M.D., F.R.C.P., F.R.C.P.(Edin), F.R.A.C.P., of University of Western Australia, Perth, and Tan Ze Feng, M.D., of the First Affiliated Hospital of Jinan University, Guangzhou, China, and both also of Royal Perth Hospital, Perth, Australia, in an accompanying editorial.

"To establish a causal relationship between insulin resistance and stroke, it is necessary to not only show that insulin resistance is an independent, significant risk factor for stroke, as reported by Rundek et al, but also that removing or minimizing exposure to insulin resistance is associated with a reduction in the incidence of stroke," they write.

Clinical trials to establish this relationship are under way, they note. In the meantime, "we can take confidence from the study of Rundek et al that measuring insulin resistance may help refine prognostic estimates of future risk of stroke obtained by means of traditional risk stratification schemes. Although it is premature to widely screen for insulin resistance as a means to prevent stroke, its measurement may have a role in particular cases in which traditional risk stratification schemes suggest that the patient is at intermediate risk of stroke (rather than high or low risk) and in whom an additional finding of insulin resistance may be sufficiently compelling to supplement lifestyle advice with pharmacological interventions to lower stroke risk."

Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by JAMA and Archives Journals.

Journal References:

T. Rundek, H. Gardener, Q. Xu, R. B. Goldberg, C. B. Wright, B. Boden-Albala, N. Disla, M. C. Paik, M. S. V. Elkind, R. L. Sacco. Insulin Resistance and Risk of Ischemic Stroke Among Nondiabetic Individuals From the Northern Manhattan Study. Archives of Neurology, 2010; 67 (10): 1195 DOI: 10.1001/archneurol.2010.235G. J. Hankey, T. Z. Feng. Insulin Resistance a Possible Causal and Treatable Risk Factor for Ischemic Stroke. Archives of Neurology, 2010; 67 (10): 1177 DOI: 10.1001/archneurol.2010.252

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Tight blood pressure control for patients with diabetes and coronary artery disease not associated with improved cardiovascular outcomes, study finds

ScienceDaily (Sep. 26, 2010) ? Patients with hypertension, diabetes and coronary artery disease who maintained their systolic blood pressure at less than 130 mm Hg did not have improved cardiovascular outcomes compared to patients with usual blood pressure control, according to a study in the July 7 issue of JAMA.

"Hypertension guidelines advocate treating systolic blood pressure (BP) to less than 130 mm Hg for patients with diabetes mellitus; however, data are lacking for the growing population who also have coronary artery disease (CAD)," according to background information in the article.

Rhonda M. Cooper-DeHoff, Pharm.D., M.S., of the University of Florida, Gainesville, and colleagues examined whether patients with hypertension, diabetes and CAD who achieved systolic BP of less than 130 mm Hg would have a reduced risk of cardiovascular events compared with those who managed to keep their systolic BP within the range of at least 130 mm Hg to less than 140 mm Hg. The analysis included 6,400 of the 22,576 participants in the International Verapamil SR-Trandolapril Study (INVEST). For this analysis, participants were at least 50 years old and had diabetes and CAD. Participants were recruited between September 1997 and December 2000 from 862 sites in 14 countries and were followed up through March 2003, with an extended follow-up through August 2008 through the National Death index for U.S. participants.

Patients received treatment with either a calcium antagonist or beta-blocker followed by angiotensin-converting enzyme inhibitor, a diuretic, or both to achieve systolic BP of less than 130 and diastolic BP of less than 85 mm Hg. Patients were categorized as having tight control if they could maintain their systolic BP at less than 130 mm Hg; usual control if systolic BP ranged from 130 mm Hg to less than 140 mm Hg; and uncontrolled if systolic BP was 140 mm Hg or higher. The primary outcome included the occurrence of all-cause death, nonfatal myocardial infarction (heart attack), or nonfatal stroke.

The primary outcome occurred in 12.7 percent (286 patients) of those in the tight-control group, 12.6 percent (249 patients) of the usual-control group, and 19.8 percent (431 patients) of the uncontrolled groups. When evaluating all-cause mortality for the entire follow-up period, after adjustment, risk of all-cause mortality was significantly greater in the tight-control group (22.8 percent) than in the usual-control group (21.8 percent).

"In this observational study, we have shown for the first time, to our knowledge, that decreasing systolic BP to lower than 130 mm Hg in patients with diabetes and CAD was not associated with further reduction in morbidity beyond that associated with systolic BP lower than 140 mm Hg, and, in fact, was associated with an increase in risk of all-cause mortality. Moreover, the increased mortality risk persisted over the long term," the authors write.

"At this time, there is no compelling evidence to indicate that lowering systolic BP below 130 mm Hg is beneficial for patients with diabetes; thus, emphasis should be placed on maintaining systolic BP between 130 and 139 mm Hg while focusing on weight loss, healthful eating, and other manifestations of cardiovascular morbidity to further reduce long-term cardiovascular risk."

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by JAMA and Archives Journals.

Journal Reference:

Rhonda M. Cooper-DeHoff; Yan Gong; Eileen M. Handberg; Anthony A. Bavry; Scott J. Denardo; George L. Bakris; Carl J. Pepine. Tight Blood Pressure Control and Cardiovascular Outcomes Among Hypertensive Patients With Diabetes and Coronary Artery Disease. JAMA, 2010; 304 (1): 61-68 [link]

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Postoperative high blood sugar appears to be associated with surgical site infection

ScienceDaily (Sep. 25, 2010) ? High blood glucose levels after surgery may be an important risk factor for infection at the surgical site in patients having general surgery, according to a report in the September issue of Archives of Surgery, one of the JAMA/Archives journals.

Surgical site infection accounts for 14 percent to 17 percent of hospital-acquired infections, making it the third most common type of infection acquired at health-care facilities and the most common among patients having surgery, according to background information in the article. "Studies have shown that these infections prolong the hospital length of stay after surgery, increase rehospitalization rates and dramatically increase the use of emergency services and health care costs," the authors write.

Ashar Ata, M.B.B.S., M.P.H., and colleagues at Albany Medical College, Albany, N.Y., reviewed the medical records of patients who had general or vascular surgery between Nov. 1, 2006, and April 30, 2009. A total of 2,090 patients were randomly selected from a quality improvement database and then matched with medical records to obtain information about postoperative glucose values. These values were available for 1,561 patients, including 559 who had vascular surgery, 226 who had colorectal surgery and 776 who had a type of general surgery other than colorectal.

Overall, 7.42 percent of the patients developed surgical site infections, including 14.11 percent of those who had colorectal surgery, 10.32 percent who had vascular surgery and 4.36 percent of those who had other general surgery.

Among general surgery patients, factors associated with surgical site infection included age, emergency status, physical status as classified by the American Society of Anesthesiologists, time in surgery, diabetes and high postoperative blood glucose (hyperglycemia). However, after adjusting for postoperative blood glucose level, all other factors were not significant predictors of infection. A subanalysis of colorectal surgery patients found that a postoperative serum glucose level higher than 140 milligrams per deciliter was the only significant predictor of surgical site infection.

Among vascular surgery patients, operative time and diabetes were the only significant predictors of surgical site infection, which was not associated with postoperative hyperglycemia.

Hyperglycemia may impair the immune system, and insulin may have anti-inflammatory and other anti-infective activities. However, it is possible that the accumulation of other risk factors for surgical site infection cause hyperglycemia rather than vice versa; hence, further study is needed, the authors note.

"In conclusion, we found postoperative hyperglycemia to be the most important risk factor for surgical site infection in general and colorectal cancer surgery patients, and serum glucose levels higher than 110 milligrams per deciliter were associated with increasingly higher rates of post-surgical infection," they continue. "If hyperglycemia is confirmed in future prospective studies with better postoperative glucose data to be an independent risk factor for postsurgical infection in general surgery patients, this would give surgeons a modifiable variable to reduce the incidence of postoperative infection."

Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by JAMA and Archives Journals.

Journal Reference:

A. Ata, J. Lee, S. L. Bestle, J. Desemone, S. C. Stain. Postoperative Hyperglycemia and Surgical Site Infection in General Surgery Patients. Archives of Surgery, 2010; 145 (9): 858 DOI: 10.1001/archsurg.2010.179

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