Critique003: Alcohol, lifestyle, diabetes

International Scientific Forum on Alcohol Research

Critique 003: 17 May 2010

Subject:  Alcohol, lifestyle, diabetes


 Article:  Joosten MM, Grobbee DE, van der A DL, Verschuren WWM, Hendriks HFJ, Beulens JWJ.  Combined effect of alcohol consumption and lifestyle behaviors on risk of type 2 diabetes.  Am J Clin Nutrition 2010;91:1777-1783.

 Authors’ Abstract

Background:  It has been suggested that the inverse association between alcohol and type 2 diabetes could be explained by moderate drinkers’ healthier lifestyles.

Objective:  We studied whether moderate alcohol consumption is associated with a lower risk of type 2 diabetes in adults with combined low-risk lifestyle behaviors. 

Design:  We prospectively examined 35,625 adults of the Dutch European Prospective Investigation into Cancer and Nutrition (EPIC-NL) cohort aged 20–70 y, who were free of diabetes, cardiovascular disease, and cancer at baseline (1993–1997).  In addition to moderate alcohol consumption (women: 5.0–14.9 g/d; men: 5.0–29.9 g/d), we defined low-risk categories of 4 lifestyle behaviors: optimal weight [body mass index (in kg/m2) < 25], physically active (≥ 30 min of physical activity/d), current nonsmoker, and a healthy diet [upper 2 quintiles of the Dietary Approaches to Stop Hypertension (DASH) diet].

Results:  During a median of 10.3 y, we identified 796 incident cases of type 2 diabetes.  Compared with teetotalers, hazard ratios of moderate alcohol consumers for risk of type 2 diabetes in low-risk lifestyle strata after multivariable adjustments were 0.35 (95% CI:0.17, 0.72) when of a normal weight, 0.65 (95% CI: 0.46, 0.91) when physically active, 0.54 (95% CI: 0.41, 0.71) when nonsmoking, and 0.57 (95% CI: 0.39, 0.84) when consuming a healthy diet.  When ≥3 low-risk lifestyle behaviors were combined, the hazard ratio for incidence of type 2 diabetes in moderate alcohol consumers after multivariable adjustments was 0.56 (95% CI: 0.32, 1.00).

Authors’ Conclusion:  In subjects already at lower risk of type 2 diabetes on the basis of multiple low-risk lifestyle behaviors, moderate alcohol consumption was associated with an approximately 40% lower risk compared with abstention.

 Forum Comments:  Whether the lower risk of diabetes among subjects in observational studies who consume alcohol is due to the alcohol drinking itself or whether, to some extent, it is due to other healthy lifestyle factors of the drinkers is a continuing question for epidemiologists.  This well-done analysis evaluated data from a very large Dutch population to determine if alcohol drinking, in addition to having optimal weight, being physically active, nonsmoking, and consuming a healthy diet, had an effect on the risk of developing diabetes. 

             The results clearly show that even among subjects who are at low risk of developing diabetes on the basis of other lifestyle characteristics, alcohol consumption provides considerably further decrease (about 40% or more) in the risk of disease.  As the authors state, their findings “indicate that the relation between alcohol consumption and type 2 diabetes is not likely to be explained by a healthier lifestyle of moderate drinkers in general.”

             Many studies have shown an inverse association between alcohol intake and body weight in women. This has been offered as one of the explanations of the inverse association between moderate alcohol intake and risk of type 2 diabetes.  For example, in the Nurses’ Health Study1 the risk of diabetes decreased monotonically with increasing alcohol consumption.  Compared with nondrinkers, women consuming 5-14.9 g of alcohol per day (about 4-10 drinks per week) had an age-adjusted relative risk of diabetes of 0.4 [95% confidence interval (Cl) 0.3-0.6]; for 15 g or more per day, the relative risk was 0.3 (95% Cl 0.2-0.4).  However, a strong inverse association between alcohol drinking and body weight explained much of the apparent protective effect of alcohol.  After simultaneous adjustment for BMI, family history of diabetes, total caloric intake, and age, the relative risk of diabetes for consumers of 5-14.9 g per day was 0.8 (95% Cl 0.6-1.2), and for women who drank 15+ g per day, the relative risk was 0.6 (95% Cl 0.3-0.9).  It is interesting that the present study demonstrates a significant reduction in risk of type 2 diabetes among moderate alcohol consumers with a normal weight.

            The authors of the present paper do not comment on beverage-specific effects, stating that a relation was not seen in a previous study by Beulens et al2 (although that paper suggested lower rates of diabetes for consumers of wine).  Also, some other studies have shown greater effects of wine than for other beverages.  For example, Hodge et al3, in a study from Australia, found significant effects on diabetes risk for women drinkers, but only for those who consumed wine.  With 800 cases of diabetes in the present study, it would have been interesting to see beverage-specific associations.

             This is an important paper, and adds to the emerging concept of including moderate drinking as one component of a “healthy lifestyle,” (one that includes not being obese, being physically active, not smoking, and eating a healthy diet.)  It reflects similar additional protection from alcohol for diabetes among otherwise very healthy subjects as was shown for heart disease by Mukamal et al4.  The results of these two studies together strongly indicate that the common suggestion by some that alcohol should be avoided since “the same protection against many diseases can be effected from other lifestyle habits” is in error.  As the authors of this paper explain, “. . . moderate alcohol consumption could be regarded as a complement, rather than an alternative, to other low-risk lifestyle habits.”

 References from Critique:
1. Stampfer MJ, Colditz GA, Willett WC, Manson JE, Arky RA, Hennekens CH, Speizer FE. A prospective study of moderate alcohol drinking and risk of diabetes in women. Am J Epidemiol 1988;128:549-558.

  2. Beulens JWJ, Stolk RP, Van der Schouw YT, Grobbee DE, Hendriks HFJ, Bots ML.  Alcohol consumption and risk of type 2 diabetes among older women.  Diabetes Care 2005;28:2933–2938.

 3. Hodge AM, English DR, O’Dea K, Giles GG.  Alcohol intake, consumption pattern and beverage type, and the risk of Type 2 diabetes.  Diabetic Medicine 2006;23:690–697.

 4.  Mukamal KJ, Chiuve SE, Rimm EB.  Alcohol consumption and risk for coronary heart disease in men with healthy lifestylesArch Intern Med 2006;166:2145-2150.

Lay Summary:  In a very well-done analysis from a large Dutch population, it was shown that moderate drinking considerably lowers the risk of developing type 2 diabetes even among subjects who are otherwise following a healthy lifestyle (not obese, non-smokers, physically active, eating a healthy diet).  Thus, it indicates that the effect of moderate drinking on lowering the risk of diabetes cannot be explained by other healthy lifestyle habits of such drinkers.  Moderate drinking should be considered as a complement, and not as an alternative, to other healthy lifestyle habits that lower the risk of chronic diseases such as diabetes and coronary heart disease.

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Contributions to this critique by the International Scientific Forum on Alcohol Research were made by  

Harvey Finkel, MD, Hematology/Oncology, Boston University Medical Center, Boston, MA, USA

Ulrich Keil, MD, PhD, Institute of Epidemiology and Social Medicine, University of Münster, Münster, Germany

Dominique Lanzmann-Petithory, MD, PhD, Nutrition/Cardiology, Praticien Hospitalier Hôpital Emile Roux, Paris, France

Erik Skovenborg, MD, Scandinavian Medical Alcohol Board, Practitioner, Aarhus, Denmark

Gordon Troup, MSc, DSc, School of Physics, Monash University, Victoria, Australia

David Van Velden, MD, Dept. of Pathology, Stellenbosch University, Stellenbosch, South Africa

R. Curtis Ellison, MD, Section of Preventive Medicine & Epidemiology, Boston University School of Medicine, Boston, MA, USA