Concern has been expressed that excessive intake of alcohol may result in hypertriglyceridemia, hypertension, and weight gain in individuals with diabetes even though, at moderate levels of consumption, this does not result in higher risk of CHD or total mortality (Koppes 2006). A limited number of studies have examined the effect of alcohol consumption on triglycerides, blood pressure, and weight in people with diabetes. Advice to avoid alcohol is often given to people with diabetes because of the assumption that even moderate amounts of alcohol will raise triglycerides and blood pressure and contribute to weight gain. However, the limited available research does not support this advice.
Triglycerides
In people without diabetes, some evidence exists to suggest that moderate intake of alcohol has no detrimental effects on triglyceride levels, even in people who are hypertriglyceridemic. Two observational studies suggested moderate consumption of alcohol had beneficial effects on triglyceride and HDL cholesterol levels. Analysis of NHANES III data from 8,125 participants revealed that mild-to-moderate alcohol consumption (1–19 drinks of alcohol per month) was associated with a lower prevalence of the metabolic syndrome and was significantly and inversely associated with three of its components—elevated triglycerides, low serum HDL cholesterol, and hyperinsulinemia (Frieberg 2004). In a study of 14,077 British women, women consuming 1–14 drinks of alcohol per week, compared to nondrinkers, had a reduction in CHD associated with the lowest triglyceride levels and highest levels of HDL cholesterol (Nanchahal 2000).
Although excessive alcohol intake, high intake of saturated fatty acids, and elevated glucose concentrations are reported to be the cause of secondary hypertriglyceridemia (especially in people with obesity) (Chait 1972), clinical trials show that the effect of moderate alcohol intake on triglycerides in people with or without hypertriglyceridemia is limited. When two alcoholic drinks or water per day for 2 weeks were consumed by people with fasting triglyceride levels of 200–750 mg/dL or by people with normal triglyceride levels (90 mg/dL), there were no significant differences reported between the effect of alcohol or the effect of water on triglyceride levels. The authors concluded that acute alcohol intake is not an important determinant of triglyceride concentrations in individuals with hypertriglyceridemia (Pownall 1999). In fact, moderate alcohol intake may actually have a beneficial effect on triglyceride levels. In a trial of healthy women, either none, one, or two drinks per day of alcohol were consumed for 8 weeks. Fasting triglyceride levels were significantly reduced by 7.8% after consumption of one drink per day and by 10.3% with two drinks per day. Fasting insulin levels decreased by 19.2% and insulin sensitivity increased by 7.2% (Davies 2002).
Only a few studies conducted in people with diabetes are available. In men with type 2 diabetes, light drinkers (<14 drinks per week) had an average triglyceride level of 115 mg/dL compared to 132 mg/dL in nondrinkers and 170 mg/dL in heavy drinkers (>14 drinks per week). Thus, triglyceride levels were significantly higher in heavy drinkers than in nondrinkers and light drinkers (Wakabayashi 2002). Subjects with type 2 diabetes either consumed wine (6.5 oz) with the evening meal or abstained for 30 days, and alcohol had no effect on triglycerides or total, LDL, or HDL cholesterol (Bantle 2008). Clearly, to answer the question of alcohol and its effects on triglyceride levels, additional clinical trials are needed, especially in individuals with diabetes. However, in individuals with high triglyceride levels (>500 mg/dL), complete abstinence is recommended along with reduced saturated fat intake to reduce the risk of pancreatitis (Miller 2011).
HDL Cholesterol
In an epidemiological study, in subjects without diabetes, 30 g alcohol a day was reported to increase HDL cholesterol by ~4 mg/dL; this, along with other positive biological marker effects, was calculated to lower risk of CHD by ~25% (Rimm 1999). In a study in people with diabetes that included the relationship of alcohol intake and HDL cholesterol, each additional drink per day was also related to increases in HDL cholesterol (~2.0 mg/dL) (Shai 2004). In a year-long study, people with type 2 diabetes ate a Mediterranean diet with either one daily 4 oz glass of wine or no alcoholic beverage; at year-end drinking wine with the Mediterranean diet resulted in a significant increase in HDL cholesterol (34.8 mg/dL) compared to the Mediterranean diet without alcohol (Marfella 2006). However, in a 30-day study, wine (24 g alcohol) with the evening meal or abstinence had no effect on HDL cholesterol (Bantle 2008). Thus, the effect of alcoholic beverages on HDL cholesterol in people with diabetes is unclear.
Hypertension
The 2010 Report of the Dietary Guidelines Advisory Committee concluded that “strong evidence indicates that moderate alcohol consumption does not elevate risk of either hypertension or stroke. It is also well documented that alcohol consumed in excess of moderate causes an increase in blood pressure and stroke” (DGAC Report 2010). There are limited available data on moderate alcohol consumption and hypertension in people with diabetes. In individuals with diabetes, a J-shaped relationship was observed between alcohol intake and blood pressure (Pitsavos 2005), and in another study, moderate drinking compared to no alcoholic beverage had no effect on blood pressure (Marfella 2006).
Weight Gain
The 2010 report of the DGAC also examined the relationship between alcohol intake and weight gain and concluded that “moderate evidence suggests that among free-living populations, moderate drinking is not associated with weight gain. However, heavier consumption over time is associated with weight gain” (DGAC Report 2010). The report does note that regardless of the alcoholic beverage, all contain calories that are not a good source of nutrients and, when consumed beyond an average of two drinks a day, may lead to weight gain. Below this level of consumption, the evidence suggests that individuals who drink in moderation do not gain weight at a faster rate than nondrinkers. Table 4.3 contains a list of alcoholic beverages and their caloric content. No studies examining the effect of alcohol consumption on weight have been done in people with diabetes.
Table 4.3 Percentage and Grams of Alcohol and Calories in Alcoholic Beverages
GUIDELINES FOR CONSUMING ALCOHOL
Information regarding benefits and contraindications should be given to individuals with diabetes so that they can make their own decisions regarding consumption of alcoholic beverages. For the majority of people, moderate consumption with food will have minimal, if any, acute or long-term effects on blood glucose levels and may have beneficial effects on insulin sensitivity and create a decreased risk for CHD.
Abstention from alcohol should be advised for individuals who cannot restrict their drinking to moderate levels; children and adolescents; individuals taking prescription or over-the-counter medications that can interact with alcohol; and individuals with medical problems such as liver disease, pancreatitis, advanced neuropathy, or severe hypertriglyceridemia. In addition, alcohol should be avoided by women who are pregnant or nursing or who are unsure if they are pregnant and by individuals who plan to drive, operate machinery, or take part in activities that require attention, skill, or coordination. Risk of unintentional injuries and breast and colon cancer should also be taken into consideration (DGAC Report 2010). No one should drink alcohol before driving.
The data do not support recommending alcohol consumption to individuals with or at risk for diabetes who do not currently drink (ADA 2008), since only observational and small clinical trials documenting the effects of alcohol are available. On the other hand, for many with diabetes, consumption of moderate amounts of alcohol does not need to be discouraged.
If alcohol is consumed, it should be consumed in moderation and only by adults. The Dietary Guidelines for Americans, 2010, defines moderate alcohol consumption as average daily consumption of up to one drink per day for women and up to two drinks per day for men and no more than three drinks in any single day for women and no more than four drinks in any single day for men (DGAC Report 2010). They also advise to drink alcohol with food to slow alcohol absorption.
The type of alcohol-containing beverage consumed does not make a difference. Because alcohol does not affect blood glucose levels or require insulin to be metabolized, occasional use of alcoholic beverages