ABNORMAL EFFECT OF CIGARETTE-SMOKING ON PITUITARY-HORMONE SECRETIONS IN INSULIN-DEPENDENT DIABETES-MELLITUS

OBJECTIVE We observed the effect of smoking two cigarettes on GH, AVP and cortisol secretion in patients with diabetes and normal subjects. DESIGN AND PATIENTS We tested 10 male smokers with insulin-dependent d iabetes mellitus (IDDM) and 10 normal smokers. On a different occasion , normal and diabetic smokers were tested with an insulin (0.15 U/kg b ody weight) tolerance test (ITT). MEASUREMENTS Hypoglycaemia-induced h ormonal responses in smokers were compared with those observed in 10 d iabetic and 10 normal non smokers. RESULTS All subjects showed similar basal GH, cortisol and AVP levels. In the normal subjects, cigarette smoking induced a significant increase in circulating GH, AVP and cort isol levels, with mean peaks 3.3, 3 and 1.58 times higher than baselin e, respectively. Smoking-induced hormonal responses were significantly higher in diabetics (mean peak was 5.2 times higher than baseline for GH, 4.0 for AVP and 1.83 for cortisol). Insulin induced a similar hyp oglycaemic nadir in all subjects at 30 minutes, even though the diabet ic subjects had a delayed recovery in blood glucose levels. GH and AVP responses to hypoglycaemia were significantly higher in diabetic (mea n peaks 11.5 and 3.2 times higher than baseline, respectively) than in normal (mean peaks 7.3 and 1.9) non-smokers, whereas these groups sho wed similar cortisol responses (mean peak 2.3 times higher than baseli ne). Smoking did not change any hypoglycaemia-induced hormonal rise in the normal controls, whereas it significantly enhanced GH, AVP and co rtisol levels (mean peaks 14.5, 4 and 3.8 times higher than baseline, respectively) in diabetics. CONCLUSIONS In patients with IDDM, cigaret te smoking not only elicits higher GH, AVP and cortisol responses than in normal subjects, but also enhances the counter-regulatory hormone responses to insulin-induced hypoglycaemia. These findings suggest int eractions between nicotine inhaled with cigarette smoking and diabetes -induced neuroendocrine alterations.