This chapter turns to diabetes, explaining the difference between Type 1, where the pancreas produces little or no insulin, and Type 2, where the body becomes resistant to it. After setting out how common the condition is around the world, it looks at the link between Type 2 diabetes and polycystic ovary syndrome, a common cause of infertility that disrupts menstruation and ovulation. It also describes how high blood sugar during pregnancy is linked to complications for the baby, such as growing larger than average. The chapter closes with ways to monitor and manage blood sugar through diet, exercise and medication, working closely with your healthcare team.