OBJECTIVE -Women with diabetes have bacteriuria more often than women without diabetes. Because Escherichia coli adhere better to vaginal cells of nondiabetic patients with recurrent urinary tract infections (UTIs) than to those obtained from healthy control subjects, it was hypothesized that E. coli adhere more to the uroepithelial cells of diabetic women, either because of substances excreted in the urine (e.g., albumin, glucose, and Tamm Horsfall protein) or because of a difference in the uroepithelial cells. RESEARCH DESIGN AND METHODS-A T24 bladder cell line and uroepithelial cells of 25 diabetic women and 19 control subjects were incubated with three different E. coli strains.RESULTS -The mean numbers of type 1-fimbriated E. coli that adhered to diabetic and control cells were 12.9 and 6.1 (P ϭ 0.001), respectively, whereas those of P-fimbriated E. coli were 8.8 and 8.1 (P ϭ 0.8), and those of nonfimbriated E. coli were 2.7 and 3.4 (P ϭ 0.4). The addition of various substances did not influence the adherence of E. coli to a T24 bladder cell line.CONCLUSIONS -Type 1-fimbriated E. coli adhere more to diabetic than to control uroepithelial cells.