To examine the associations between cigarette smoking, connective tissue changes, and diabetic retinopathy, a detailed smoking history was elicited from 150 normotensive non-diabetic subjects, and from 266 randomly selected adult patients with Type 1 diabetes, after examination for limited joint mobility, Dupuytren's contracture, and diabetic retinopathy. Mean insulin dose and current glycosylated haemoglobin concentrations were comparable in diabetic smokers and non-smokers. The historical duration of smoking correlated with the duration of diabetes (r = 0.72, p less than 0.001). In diabetic patients limited joint mobility was positively associated with retinopathy, being found in 73/147 (50%) patients with retinopathy compared with 20/114 (18%) without retinopathy (chi 2 = 28.9, p less than 0.001), and also with Dupuytren's contracture, 19/34 (56%) of patients with limited joint mobility having Dupuytren's contracture, compared with 76/232 (33%) of patients without Dupuytren's contracture (chi 2 = 7.05, p less than 0.01). Limited joint mobility was observed in 50% of diabetic smokers compared with 25% of non-smokers (odds ratio = 2.87 (corrected for diabetes duration), 95% confidence interval 1.64-5.01). Diabetic retinopathy was weakly associated with smoking (odds ratio 1.09; 95% confidence interval 0.60-1.96). There was however an increased prevalence of background retinopathy among male smokers (50% vs 29%; chi 2 = 6.88, p less than 0.01). In non-diabetic males limited joint mobility was observed in 37% of smokers but only in 11% of non-smokers (NS), while 33% of smokers and 8% of non-smokers had Dupuytren's contracture (p = 0.012). These results suggest that cigarette smoking contributes to the development of extra-articular connective tissue changes in both diabetic patients and non-diabetic subjects, and possibly to the development of diabetic retinopathy.