Two-hour glucose and insulin responses after a standardized oral glucose load in relation to serum gamma-glutamyl transferase and alcohol consumption.

In a population study of 4,763 middle-aged men, the 120-min responses of blood glucose as well as plasma IRI in OGTTs were studied in subgroups of the screening population with different levels of gamma-glutamyl transferase (GGT) and/or defined alcohol consumption levels. In the group with low GGT (below the median, n - 2,196), both 120-min blood glucose and plasma IRI tended to be lower than in the whole screening cohort and there was a significantly smaller number of cases with 120-min blood glucose greater than or equal to 7.0 mmol/l. In a group of ideological alcohol abstainers the values of fasting as well as 120-min blood glucose were largely the same as in the average middle-aged men. In members of the study population with increased screening GGT, however, both fasting and especially, 120-min values of blood glucose and plasma IRI were higher than in the average males, particularly in the cases in which the interview revealed chronic heavy alcohol consumption as the predominant underlying factor associated with elevated GGT. In these individuals, the prevalence of 120-min screening OGTT blood glucose values greater than or equal to 7.0 mmol/l was 26%, in comparison with 13% in the average men and 9% in the individuals with screening GGT left of the median. This indicates that GGT and alcohol consumption are of clinical importance both for the results and interpretation of OGTTs.