Author's note: The numbers in red correspond to the numbered entries in the bibliography.
We are all aware of the analogy about one's diabetes control being like riding a roller-coaster. The goal is to turn the roller-coaster into a go-cart running on a flat track. We want to eliminate the extreme ups and downs and keep things on an even keel. But a woman with diabetes gets to ride an additional roller-coaster at the same time; the extra ups and downs are caused by her menstrual cycle.
Many women report an elevation of blood glucose occurring from three to five days prior to the beginning of their menstrual periods. Blood sugars typically return to normal levels within the first day or two after the period starts. One medical study, conducted in England in 1993, (1) found that as much as 67% of diabetic women reported premenstrual changes in their blood glucose levels and 70% reported changes during menstruation. These changes seem to be more prevalent in women who also suffer from other premenstrual symptoms.
This same study also found that the age at which menstruation first starts (menarche) is greater in women with diabetes than in those without. Another study, conducted in Denmark in 1987 (2), found that for girls who develop diabetes before age ten, menarche occurs an average of one year later than for non-diabetic girls. Also, women with diabetes are more likely to experience irregular menstrual cycles than non-diabetic women.
Also of interest are the results of yet another British study published in 1991. (3) Evidence indicates that pre-pubescent girls may begin exhibiting a cyclical disturbance in their blood glucose control as early as age nine. Generally, the result is hyperglycemia (high blood sugar) although in some instances, hypoglycemia (low blood sugar) occurs. Typically this disturbance occurs at 21-34 day intervals and lasts from two to five days. Parents of young diabetic girls are encouraged to watch for such a cycle to develop as steps can be taken to improve glucose control during this time.
What causes premenstrual changes in blood glucose? Probably the increase in female hormones estrogen and progesterone that occurs after ovulation. One theory is that increased levels of progesterone cause increased insulin resistance. This in turn leads to hyperglycemia. While most women report premenstrual increases in blood sugar, some do experience hypoglycemia during this time. This could be due to high levels of estrogen causing increased insulin sensitivity. For more information on this please read Diabetes Control and a Woman's Menstrual Cycle by David Fitz-Patrick, M.D. of the Diabetes & Hormone Center of the Pacific in Hawaii.
Another explanation that is frequently given is that the cravings for carbohydrates which accompany premenstrual syndrome are to blame for elevated blood sugars. While it is true that women often have increased appetites and cravings during the days leading up to menstruation, this cannot be the sole cause of premenstrual hyperglycemia. Women who use an insulin infusion pump have the advantage of being able to deliver precise amounts of insulin and can balance the insulin to the amount of carbohydrate intake. Several women who are diligent about bolusing the correct insulin dose for everything that crosses their lips still report having a premenstrual blood sugar rise. This suggests that the hormonal changes are the real reason for the increase.
Menopause also presents challenges to a woman's blood glucose control. The same problems of premenstrual hormone increases are prevalent, only in reverse. During menopause, production of progesterone and estrogen diminishes. A decrease in progesterone levels results in increased insulin sensitivity, and on the flip side, decreased estrogen can increase insulin resistance. It all depends on which hormone seems to have more control. If menopause is interfering with your diabetes control, you should discuss the problems with your doctor. One possible solution is Hormone Replacement Therapy. This treatment has potential drawbacks and all aspects should be carefully considered before beginning HRT. It is also important to maintain healthy eating and exercise habits throughout menopause and after. For more information on this topic, see Diabetes and Menopause by David Fitz-Patrick, M.D. of the Diabetes & Hormone Center of the Pacific.