|No acute changes in blood glucose, but extreme changes in insulin levels. How can this trigger a reduction in glycated albumin - How's that possible?|
If you know that, the observations researchers from the Fudan University in Shanghai report in their latest study probably won't come as a surprise. In their investigation into the pharmacokinetics and pharmacodynamics of GABA in healthy volunteers, the researchers found that the chronic provision of 2g of GABA three times per day triggers a highly significant decrease in glycated albumin (GA) levels, the intermediate measure of blood glucose control (in-between acute blood glucose measurements and HbA1c | Roohk. 2008), within only 7 days.
|Figure 1: Acute glucose (top) and insulin (bottom) response after single and repeated administration of 2g of GABA (left). Chronic effects of repeated dose-administration of GABA on glycated albumin (right | Li. 2015).|
Glucose, insulin and glucagon: Let's briefly recap how the three are related. To lower your glucose levels, your body produces insulin which will then tell your cells suck the glucose from the bloodstream. If the glucose levels are getting lower and lower, your body produces glucagon which will then trigger a cascade of events to increase your blood glucose levels. This can be done by mobilizing stored glycogen (mostly from the liver) or producing new glucose via gluconeogensis - a process that relies heavily on amino acids, first and foremost alanine and glutamine.Usually, this 1.4-fold or 1.6-fold increase in insulin should trigger a significant (at least transient) decrease in blood glucose. Since the latter wasn't the case in either the fasted or the fed tests the scientists conducted on the twelve subjects, who participated in the open-labeled, three-period trial, it appears more than counter-intuitive that the chronic administration of GABA which does not accumulate in the body and was found to be almost completely absorbed in 60 minutes and to have a half-life of 5h still lead to an GA decrease of approximately 11-12%.
Now this obviously confirms that GABA, due to its ability to increase islet hormonal secretion, has potential therapeutic benefits for diabetes, what the study does not tell us, though, is whether the lack of immediate effects on blood glucose levels can, as the scientists suspect, "in part be attributed to GABA-induced counter regulatory mechanisms, especially elevated glucagon" (Li. 2015) which rose so that the insulin-to-glucagon ratio remained unchanged. Yet while the latter could explain why the subjects did not become hypoglycemic in the face of increased insulin levels, the lack of certainty with respect to the underlying mechanisms makes the study results difficult to interpret.
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