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Fasting Insulin Guidelines


Eleanor Kellon, VMD
 

This is the abstract from the recent study on fasting insulin showing the cutoff of 20 uIU for normal was way too high:

Comparison of fasted basal insulin with the combined glucose-insulin test in horses and ponies with suspected insulin dysregulation

Highlights

Basal (fasting) insulin is a convenient test of insulin dysregulation.

Previous cut-offs had poor sensitivity (15%) for diagnosis of insulin dysregulation.

Use of a receiver operating characteristic curve-derived cut-off improved the sensitivity (63%) of basal (fasting) insulin.

Specificity (87%) was maintained with this technique.

Abstract

Fasting horses for measurement of basal serum insulin concentration (fasting insulin; FI) has been recommended to standardise testing for insulin dysregulation (ID), yet limited data exist comparing it to dynamic tests. This study aimed to compare FI with the combined glucose-insulin test (CGIT) in horses suspect for ID. We hypothesised that FI would have poor sensitivity for detecting ID compared to CGIT using conventional cut-offs. Records were retrieved from CGITs performed in horses fasted for approximately 8 h. Serum insulin and glucose concentrations were measured before and for 150 min following an IV bolus of glucose followed by insulin. Correlations between FI and CGIT values were assessed. Youden’s index analysis was used to determine the optimal cut-off for FI. Logistic regression and Mann–Whitney U tests were used to determine factors affecting the results.

CGITs (n = 130) from 62 horses were evaluated. Compared to CGIT, sensitivity and specificity of FI for diagnosis of ID were 14.6% and 100% at a cut-off of 20 μIU/mL and 63.4% and 87.2% at a cut-off of 5.2 μIU/mL, respectively. FI was significantly correlated with insulin at 45 min (rs = 0.66) and 75 min (rs = 0.72); area under the curve for insulin (AUCinsulin; rs = 0.67); glucose at 45 min (rs = 0.53); and AUCglucose (rs = 0.50). Obesity was significantly associated with increased odds of a positive CGIT and horses with a positive CGIT were significantly older (P < 0.05). In conclusion, FI correlated well with CGIT results and had adequate sensitivity and specificity at lower cut-offs, despite poor sensitivity at conventional cut-off values. Further research to derive cut-off values relevant to the fasting period is warranted.



--
Eleanor in PA

www.drkellon.com 
EC Owner 2001


Cheryl Oickle
 

Very Interesting document.  
A question: Jewels fasting insulin and glucose were within normal limits 2 years ago, every time now she is tested her glucose is less than 6 but insulin is greater than 100. At the time of the blood draws, she has either JUST finished her feed or is still eating a feed.
Could some one reflect on this given this recent find.
Thanks


--
Cheryl and Jewel
Oct 2018
Port Alberni BC Canada
https://ecir.groups.io/g/CaseHistory/files/Cheryl%20and%20Jewel
https://ecir.groups.io/g/CaseHistory/album?id=81063


LJ Friedman
 

im unsure  i understand the takeaway here?
We currently do not fast for insulin. does this study suggest a change to fasting insulin? 
--
LJ Friedman  Nov 2014 Vista,   Northern  San Diego, CA

Jesse and majestic ‘s Case History 
Jesse's Photos

 


Eleanor Kellon, VMD
 

The point of the article is that fasting "normal limits" are too high. If you apply their recommendations, her fasting insulins were above normal.

Post meal insulin depends on the composition (sugar and starch) of the meal, and whether it followed an overnight fast. The first meal of the day after an overnight fast will produce a higher insulin response and that last about 4 hours. Otherwise, very low sugar and starch meals produce low insulin responses that peak at 1 to 1.5 hours after eating.
--
Eleanor in PA

www.drkellon.com 
EC Owner 2001


Eleanor Kellon, VMD
 

It only says if you do fast the upper limit of normal needs to change.
--
Eleanor in PA

www.drkellon.com 
EC Owner 2001


LJ Friedman
 

If a horsec fasts overnight and feed the first meal of the day at 7 AM, would if that makes sense to test after the second meal of the day? 
--
LJ Friedman  Nov 2014 Vista,   Northern  San Diego, CA

Jesse and majestic ‘s Case History 
Jesse's Photos

 


Sherry Morse
 

LJ, in that scenario you'd want to test at 11am or later, but bear in mind that if you do a feed later in the day you still don't want to test right afterwards due to the bump in insulin from a hard feed.




Eleanor Kellon, VMD
 

For insulin testing, remember the best and simplest is to keep hay available through the night before and day of testing with no other feeding.
--
Eleanor in PA

www.drkellon.com 
EC Owner 2001