Although it does not occur in every woman, blood sugar levels tend to be higher three to five days before, during and after menstruation. As hormone levels change throughout a woman’s cycle, blood sugar levels fluctuate when estrogen levels increase. The increase in estrogen signaling the start of menstruation can make the body insulin resistant to its own insulin or injected insulin. Each month hormone levels fluctuate, insulin dosages need to be adjusted if a woman experiences higher blood sugar levels. Extra insulin taken during menstruation can help overcome insulin resistance that occurs naturally. Many women experience cycles that do not occur every four weeks. Cycles can range from as short as 20 days to as long as 40 days or more. According to Diabetes Self-Management, studies found that women with Type 1 diabetes had more menstrual problems before the age of 30 than women without diabetes. Women in the study with Type 1 diabetes were categorized as having menstrual problems that consisted of longer cycles and heavier menstruation.