Protein, Insulin-like Growth Factor-1 (IGF-1) and Glucose Homeostasis

I've blogged previously on the LoBAG diets for treatment of diabetes.  These diets are higher in protein that standard recommendations - 30% vs. 15% - with varying carb content (20,30 & 40% have been studied).  With both of the lower carb diets, this group has achieved good improvements in HbA1c levels in relatively short time (5-10 weeks).  In comparing their diets  they observed:
Increasing the protein content of the diet from 15 to 30% resulted in an 35% increase in IGF-I regardless of whether the carbohydrate content was 40%, 20%, or 30% as in the present study. Thus the dietary protein-induced increase in IGF-I is independent of the amount of dietary carbohydrate and fat.
I believe the near-OCD obsession with insulin in the LC community overshadows the vast body of research on other hormones and peptides that's out there and their role in metabolism.

I've frequently heard that diabetics should limit protein, for example, because excess is turned to sugar.  This nugget of information is often traced to Dr. Bernstein - whether he states this or not, I do not know.  I've not read his books.  If anyone has a citation, I would appreciate it.   But clearly this is not the case demonstrated by the findings of these researchers.  

Anyway, I came across this article recently:  
Relationships between serum IGF1 levels, blood pressure, and glucose tolerance: an observational, exploratory study in 404 subjects

The Intro is chock full of interesting info so I'm C&P'ing it in its entirety.

Growth hormone (GH) is principally involved in the regulation of somatic growth, and exerts its effects either directly or indirectly, by stimulating the production of insulin-like growth factor-1 (IGF1) that mediates GH action on peripheral tissues (12). IGF1 levels are strongly determined by changes in GH secretion; they are low in patients with GH deficiency (GHD) and high in those with acromegaly (12). Age and sex also affect serum IGF1 concentrations; at the age of 65 years, daily spontaneous GH secretion is reduced by 50–70% and consequently IGF1 levels decline progressively (3), while male gender is associated with higher IGF1 levels than females (4).
Besides, GH and IGF1 are anabolic hormones, so that malnutrition and other catabolic states, such as severe trauma and sepsis, reduce serum IGF1 concentration. Patients with insulin-dependent diabetes have some hepatic resistance to GH, with elevated serum GH levels and reduced IGF1 levels (5). Moreover, subtle changes in IGF1 levels in the general population are associated with changes in blood pressure (BP) and insulin sensitivity: IGF1 levels in the upper normal range are associated with reduced BP (6) and vascular tone (7), increased insulin sensitivity (89), and reduced prevalence of diabetes mellitus(10). Epidemiological studies have suggested that IGF1 levels in the lower normal range are associated with an increased risk of ischemic heart disease (11,1213) and stroke (14151617). In this setting, a protective role in the development of atherosclerosis was suggested for free IGF1 levels (17). We also reported the existence of tight relationships between IGF1, IGF binding protein 3 (IGFBP3), and a surrogate marker of atherosclerosis such as the measurement of intima-media thickness (IMT) of common carotid arteries in a group of 174 healthy individuals (18). We found that IGF1 levels were the best predictors of total cholesterol levels and total/high density lipoprotein (HDL) cholesterol ratio; additionally, mean IMT was best predicted by subjects' age (as expected), but IGF1 and IGFBP3 were its second best predictors (18).
The study itself is not all that remarkable.  They looked at the relationship between IGF-1 levels and blood pressure and diabetes.  I think the plots of the results are more impressive than reading the numbers:

I was looking about the web on IGF-1 as it would seem to make a good treatment for diabetes.  Apparently it's been around the bodybuilding/athlete circuits as an anabolic agent for some time.   

I was also reminded of an article I read about increased protein needs as we age.  I'll try to dig that one out of the docs folder when I get a chance.  But given how IGF-1 levels drop as we age, it would seem reasonable that we should increase protein to help boost it.  


Mario Iwakura said…

Regarding IGF-1 as a treatment for diabetes, actually there is a small trial on supplementation of bovine colostrum (high in IGF-1) in type 2 diabetics:
MM said…

I remember in GCBC, Taubes seemed to think there was a link between IGF and cancer. I was going to type some of it out, but there's too much. So, I'll link to the pages on google books.

It's mainly 215-217. Since I know very little about IGF I was never sure what to think of this. It does seem that a lot of what Taubes wrote in his book is sort of half-truths. This chapter may be included in that. What is your opinion?
Bill said…
@ Mario, interesting paper ( Fasting glucose decreased by over 10% and ketones dropped dramatically. CS (and Mario), what do you think happened to their livers? Hepatic TG content?
CarbSane said…
@MM: I just bookmarked two papers over in my library: here and here that indicate our problems with aging may be decreasing IGF-1 production. So, again, I think the key is that cancer cells have more receptors to utilize yet another life-force hormone that Taubes seems to be demonizing by implication out of context.
CarbSane said…
@Mario: Cool!

@Bill: The marked decrease in FBG would indicate an improvement in hepatic insulin sensitivity. I'll bet their NEFA go down as well which would be the means by which fasting trigs are reduced on a normal diet.
Mario Iwakura said…

I'm by no means an expert, but to me in the ethyology of diabetes pathogens, a bad diet and endocrine disruptors (like chemicals, heavy metals, etc) are all involved, leading to alterations in gut microbiota and gut permeability (ok, I'm a fan of Paul Jaminet's theories!).

Both, colostrum and IGF-1 seems to reduce intestinal permeability. Colostrum also seems to induce a healthy gut microbiota.

IGF-1 and gut permeability:

Colostrum and gut permeability:

Colostrum and healthy gut microbiota:

Diabetes type 2 and gut permeabitily/microbiota:
CarbSane said…
Wowsers Mario! Thanks - I just bookmarked those over in my library blog.
Mario Iwakura said…

You forgot to bookmark the first study, wich seems to be the corollarie of the later ones!

Anyway, Pubmed just sent me this one:

I know that rat models of diabetes are not really aplicable to human diabetes, but I think this will be interesting to you... ;-)
Mirrorball said…
This comment has been removed by the author.
Debbie Cusick said…
I never know WHAT to eat these days. Eating nothing kills you from starvation, and eating *anything* causes some sort of adverse reaction or other. Eating a high (over 20%) protein does DOES make my blood sugar skyrocket.
CarbSane said…
scall0way: If you were to eat chicken breast and green salads with lemon juice and olive oil, you're telling me this would cause blood sugars to skyrocket?

Whey protein is a different animal. I'm not even diabetic or anywhere close and that 6WC messed with my blood sugars. But for me, that diet amounted to like 60% protein.
Mr. Wrong said…
Taubes was probably referring to the studies on the Laron Dwarfs and possibly to the 'sweet16' gene DAF 16.