Three prospective epidemiologic studies have suggested that smoking is a risk factor for non-insulindependent diabetes mellitus (NIDDM) (1-3). Feskens and Kromhout (1) reported a 3.3 times higher risk of NIDDM among Dutch men who smoked 20 or more cigarettes per day than among never smokers; and in US health professionals (male and female), Rimm et al. (2, 3) found a 1.4-1.9 times higher risk among those who smoked 25 or more cigarettes per day. These studies controlled for other risk factors for NIDDM. The findings are consistent with those from laboratory studies which have suggested that smoking causes increased insulin resistance in peripheral tissues
(4, 5) and increased levels of glycosylated hemoglobin (6). However, other epidemiologic studies have failed to show effects of smoking on the incidence of diabetes (7, 8), although this might be attributable to the fact that these studies did not take into account the exact number of cigarettes smoked per day.