Moderate drinking can help women with type II diabetes, says studyBMJ 2002; 324 doi: https://doi.org/10.1136/bmj.324.7348.1236/a (Published 25 May 2002) Cite this as: BMJ 2002;324:1236
Moderate alcohol intake may help control blood sugar in postmenopausal women with type II diabetes and may prevent the development of the disease and its cardiovascular sequelae in women at risk, a new report says (JAMA 2002;287:2559).
Researchers from the US Department of Agriculture's Beltsville Human Nutrition Research Center in Beltsville, Maryland, decided to study the effect of alcohol intake in postmenopausal women because alcohol has hypoglycaemic effects and the postmenopausal state is associated with an increased prevalence of insulin resistance, with resultant relative hyperglycaemia.
The insulin resistance or reduced insulin sensitivity leads to hyperinsulinaemia, high concentrations of circulating blood glucose, and a greater risk of cardiovascular disease risk than in the premenopausal state. Moderate alcohol intake has also been shown to be cardioprotective, through a shift in lipid metabolism towards high density lipoproteins.
The investigators, led by Dr Michael Davies and Dr Philip Taylor, recruited 102 postmenopausal women in a randomised, crossover study that compared the effects of 0, 15, or 30 grams per day of alcohol on fasting insulin, triglyceride, and blood glucose concentrations and insulin sensitivity.
Eligibility criteria for the study included being aged 50 years or more, of good general health, postmenopausal for at least a year, no personal or family history of alcohol misuse, no use of hormone replacement therapy, and not taking any drugs that would interfere with carbohydrate or lipid metabolism.
Diet was controlled, and vitamin and mineral supplements were forbidden during the study period. The participants had to be within 90%-140% of their ideal body weight.
Of the 102 women screened, 63 were entered into the study and 53 completed it. They received $3000 for participating in the study, during which their diet was controlled for eight weeks at a time. The crossover design was such that each woman was tested in all three alcohol content arms.
Each dietary period was followed by a 2-5 week washout period to eliminate any bias from previous treatment. Menus provided 54% of calories from carbohydrates or from carbohydrates and alcohol, 32% from fat, and 14% from protein. Calorie intake was adjusted to maintain constant body weight.
Alcohol was provided as ethanol in orange juice. The participants were not told the alcohol content of their drinks.
For women in the 0 g/day arm, an isocaloric beverage was given. The researchers found that women who consumed 30 g/day, equivalent to just under four units a day, reduced their fasting insulin concentrations by 19% (P=0.004) and their triglyceride concentrations by 10% (P=0.001), compared with when they were in the 0 g/day arm.
Despite the reduction in fasting insulin concentrations, blood glucose concentrations were maintained. This translated into an improvement of insulin sensitivity of 7%. Responses did not differ significantly between normal weight, overweight, and obese women.
Improvements with 15 g/day of ethanol were less marked and affected only fasting triglyceride concentration, with a 8% (P=0.03) reduction, compared with no alcohol.
While the study is interesting it is unclear if all the benefit could be attributed to the addition of alcohol rather than to the reduction in carbohydrate intake. The authors state: “By design total carbohydrate intake was reduced with increasing alcohol intake. Energy from carbohydrates decreased from 53% with 0g/d of alcohol to 42.2% with 30g/d of alcohol.”
Moreover, it is unknown whether these results are specific to pure ethanol rather than to commercial drinks and it is unknown if these results could be replicated in diabetic woman on non controlled diets. Alcohol consumption contributes to hypoglycaemia because its metabolism inhibits gluceneogenesis in the liver. This study suggests that it may also have a role in reducing insulin resistance.