How does my menstrual cycle affect my insulin needs?

Yes, it is entirely hormonal, and you are definitely not imagining it! The menstrual cycle is one of the most significant, yet least discussed, variables in daily diabetes management for women.

Your cycle is driven by two main hormones: estrogen and progesterone. In the days leading up to your period (the luteal phase), your progesterone levels peak. Progesterone actively increases insulin resistance. For many women, this means blood sugars run stubbornly high for three to seven days before their period begins, and standard correction doses seem completely ineffective.

Then, just as your period starts, those hormone levels plummet. This sudden drop removes the insulin resistance, causing your sensitivity to skyrocket back to normal. If you are still taking the higher doses of insulin from the days prior, this rapid shift can cause severe, unexpected low blood sugars.

To manage this monthly roller coaster, the best strategy is to track your cycle alongside your blood sugars for a few months to find your specific pattern. Once you see the trend, you can work with your endocrinologist to create a separate "pre-period" basal profile on your pump, or temporarily adjust your long-acting insulin doses on injections, to safely counteract those hormone surges.