We herein show that even though over half of the women with T1D had been on an individualized diet since before pregnancy, had received adequate counseling on the importance of controlling rapid weight gain to avoid hyperglycaemia and macrosomic babies, and had followed a reported reasonably good dietary regime throughout pregnancy, insulin up-titration was required to maintain good glucose control so as to prevent significant weight gain. The gene discussed is INS; the disease is type 1 diabetes mellitus.