Nicotine infusion acutely impairs insulin sensitivity in type 2 diabetic patients but not in healthy subjects

Objectives. The aim of this study was to examine if an acute nicotine infus ion alters insulin sensitivity to a similar degree in type 2 diabetic patie nts as in healthy control subjects. Design. Double-blind, cross-over, placebo-controlled, randomized experiment al study. Nicotine 0.3 mug kg(-1) min(-1) or NaCl was infused (2 h) during a euglycaemic hyperinsulinaemic clamp (4 h) to assess insulin sensitivity. Setting. University research laboratory. Subjects. Six male and female type 2 diabetic patients [DM2: age 54 +/- 10 (mean +/- SD) years; body mass index (BMI) 25.6 +/- 2.9 kg m(-2)] treated w ith diet or one oral hypoglycaemic agent and six age- and BMI-matched contr ol subjects (Ctr). Main outcome measures. Insulin sensitivity (rate of glucose infusion per kg fat free body mass and minute), nicotine and free fatty acid (FFA) levels, pulse rate and blood pressure, Results. The infusions produced similar nicotine levels in both groups. In the absence of nicotine, DM2 were more insulin resistant than Ctr (6.7 +/- 0.4 vs. 10.9 +/- 0.3 mg kg(-1) LBM min(-1), respectively; P < 0.0001). This insulin resistance was further aggravated by the nicotine infusion in DM2 but not in Ctr (4.6 <plus/minus> 0.3 vs. 10.9 +/- 0.3 mg kg(-1) LBM min(-1) ; P < 0.0001). Only minor differences were seen in FFA levels, pulse rates and blood pressure. Conclusions. At this low infusion rate, nicotine aggravated the insulin res istance in DM2 but not in Ctr. This finding may be because of the (dysmetab olic) diabetic state per se or to an increased sensitivity to environmental factors associated with a genetic predisposition for type 2 diabetes. Thes e results show that diabetic subjects are particularly susceptible to the d etrimental effects of nicotine.