To investigate the association of familial history (FH) of diabetes with the glycaemic control status of patients with type 2 diabetes (T2D), a cross-sectional study using stratified cluster sampling was conducted with 20,340 diabetic patients in Jiangsu, China. In total, 21.3% of the subjects reported a FH of diabetes. Patients with a FH of diabetes showed a higher risk of poor glycaemic control (59.7%) than those without a diabetic FH (49.8%), with an odds ratio (OR) of 1.366 (P < 0.001). Glycaemic control status did not significantly differ between the T2D patients with parental FH and those with sibling FH. Compared with patients with paternal FH, patients with maternal FH had a higher risk of poor glycaemic control (OR = 1.611, P = 0.013). Stratified analyses showed that a FH of diabetes was significantly associated with poor glycaemic control among T2D patients with a low education level (P < 0.05). In the <60 years old, overweight, and low level of physical activity groups, patients with a maternal history of diabetes showed a higher risk of poor glycaemic control than those without a FH (P < 0.05). In conclusion, FH of diabetes, especially a maternal history, had an independently adverse effect on the glycaemic control of T2D patients.