Hypoglycemia Unawareness of a Different Kind: Surprise Lows
I have written about the honeymoon period, symptoms and signs of hypoglycemia, the use of glucagon, etc., and now am entering somewhat of an unknown territory when I write about hypoglycemia that arises out of nowhere. At the end of the honeymoon period (lasting different lengths of time for each individual) I am sure that many people with diabetes have experienced hypoglycemia without any known precipitating events. We are talking about the times when for absolutely no reason, you begin to run low for a few days and have to either cut down basal insulin or stop bolusing for carbohydrates to avoid severe hypoglycemia. Some families have even informed me that they had to discontinue all insulin for a few days and then blood sugars began to rise with the gradual reinstitution of previous insulin doses.
I have thought about this mystery and developed some possible theories as a result of evidence-based literature. I have recently become aware of several snippets of interesting information: after attack by killer T cells, pancreatic islet cells continue to regenerate, only to be once again targeted by the immune response. The key fact is that B cells do regenerate. We know this to be true based on the recent Joslin report in which pancreases of people with diabetes more than 50 years (after a natural death) were shown to have some islet cells remaining, and as demonstrated by additional research, functioning B cells. What does this mean? Well, it appears that if we can remove the offending autoimmune attack, the B cells seem to have the ability to regenerate. The halt of the autoimmune attack has been the focus of the monoclonal antibody studies that have recently failed to reach efficacy.
What if there was a theoretical regeneration of a finite number of beta cells that puffed out insulin unexpectedly? Perhaps this may be a reason for some of these unexpected low blood sugars.
There are other reasons of course for unexpected lows that may have a more conventional physiologic explanation.
- After a severe low blood sugar in which your body breaks down stored glucose in the liver (glycogen) to attempt to raise serum blood sugar, it takes time for the liver to re-accumulate glucose and begin glycogenesis. Thus, it may take large amounts of ingested carbohydrate to metabolize glucose into glycogen. We know this to be true based on the experience of multiple attempts to increase blood glucose every 15 minutes. It sometimes takes a while to keep blood glucose concentrations at a steady state. In addition, after a severe low, or several severe lows in a row, the body may not be able to keep blood sugars stable as there may be no glycogen left in storage2. Increased insulin sensitivity due to exercise–post-exercise induced hypoglycemia that may even last 36 hours!
- Hormones! I typically hear in my female patients that menstrual periods wreck havoc with blood sugars. There are several patterns that I have noted. The first pattern is such that several days prior to menstruation, blood sugars increase significantly and then as soon as menses begin, blood sugars drop precipitously due to the interplay of hormones. Some women have noted the exact opposite pattern. The key is to determine if a pattern exists to be prepared!
- Illness–We have seen that illness may precipitate both low and high blood sugars. Stress hormones clearly do play role to elevate blood sugars. But why do some people become low (even if they are keeping fluids down and consuming carbohydrate)? Could it be that the immune system is busy doing what it is actually supposed to be doing in terms of fighting foreign invaders instead of its own self? Of course, I am speculating based on the “hygiene” hypothesis that formulates a possible reason for autoimmunity. The hygiene hypothesis postulates that as we have less exposure to antigens with improved living conditions with resultant less illness, our underactive immune system will attack self and thus place us at risk for developing autoimmune disease. Perhaps in infancy, our thymus does not totally learn to distinguish between self and not self.
Keep those carbohydrates available at all times.
Fran Cogen, M.D., C.D.E., is the director of the Childhood and Adolescent Diabetes Program at Children’s National Health System. She wrote about diabetes for HealthCentral.