Letters to the Editor
Animal Insulin Ally
At the same time, I do not believe that the clinical literature supports the belief that human insulin's differential actions on the brain lead to an increase in hypoglemic unawareness. I do believe, however, the anecdotal evidence that people switched from animal to human insulins experienced an increase in hypoglycemia unawareness.
In most people, the peak of human insulin action occurs sooner than the peak of animal insulin when you compare the formulations (human v. animal R, human v. animal N, etc.). In addition, there are some people in whom human NPH peaks in four hours. They cannot be well-controlled on two- or three-shot regimens using human insulins, whereas they might have success with the regimen if they switch to pork or beef NPH. Also, for people on multiple daily injections (MDI) human ultralente is not peakless (while beef ultralente is), even when the human U is given in two injections. This can complicate MDI regimens.
So, for reasons of better control in specific patients, we need to bring back beef ultralente and keep the other animal insulins!
I believe people can experience more lows and therefore hypoglycemia unawareness with human insulin after switching from animal insulin. This happens for the straightforward reason that hypoglycemia causes hypoglycemia unawareness. This hypoglycemia may be caused by the better control, coupled with enhanced scrutiny during the switch.
These problems can be prevented by warning patients to do extra tests to determine the optimal timing of meals and snacks when switching from one insulin to the other. I am fairly certain this is not routinely done. This may also explain why controlled clinical studies do not demonstrate meaningful differences in hypoglycemia unawareness during an insulin switch: clinicians in these studies are informing patients about the differences in human versus animal insulins. Better informed patients are able to prevent hypoglycemia and therefore hypoglycemia unawareness.
Until someone recruits a number of people with long-standing diabetes, induces increased levels of hypoglycemia using human insulin one time and animal insulin another time, and then measures couterregulatory hormone responses, autonomic and neurologlycopenic symptom scores and tests cognitive function at all glucose concentrations, we will not have convincing evidence of specific differences created by different insulins.
In the meantime, we have important and proven reasons to keep animal insulins.
Better Control With the Pump?
I am responding to the recent article in DIABETES HEALTH entitled "Patients Experience Less Hypoglycemia When Using a Pump."
Although I feel the study reveals important information relating to HbA1C levels and pump use, I have a problem with the article and the study. Both imply that switching to a pump results in lower incidence of hypoglycemia. The major problem with this study is that there is no control group.
Simply switching to intensive therapy may have resulted in an increase in hypos for many of the subjects as they acclimated themselves to their new regimen. As participants become familiar with the intensive therapy and control improves, the number of hypos may subside, but the result is a greater number of recorded hypos in the first year of intensive therapy. Since these participants undoubtedly used intensive therapy while on the pump, they did not experience a drastic change in therapy. Had there been another group that continued on intensive therapy without the pump, they too might have shown a decrease in hypos during the second year. The fact that HbA1C values did not change when participants switched to the pump further indicates that pump use may not improve BG control over intensive therapy.
Wythe Whiting, IV
Georgia Institute of Technology
DIABETES HEALTH Board member, Bruce Bode, M.D., responds:
Thank you for your comments. This study's control group consisted of patients using multiple injections of insulin for up to ten years before starting on the pump. The average length patients were on multiple injection therapy was two years before going on the pump. There was no significant change in severe hypoglycemic frequency from1 the first year on a pump to years two, three, four and beyond; however, there was a significant drop in hypoglycemic frequency when comparing any year on the pump with any year using multiple injections.Click Here To View Or Post Comments