🍪 CompoundTalk uses cookies to improve your experience, analyze traffic, and personalize content. By continuing to use this site, you agree to our Cookie Policy.
Evidence-based GLP-1 & peptide discussion since 2023
ForumsMetabolic Health & DiabetesInsulin sensitivity vs insulin secretion — how GLP-1 agonists differ from insulin

Insulin sensitivity vs insulin secretion — how GLP-1 agonists differ from insulin

Dr.MetabolicMD Sat, Mar 7, 2026 at 3:59 AM 7 replies 348 viewsPage 1 of 2
Dr.MetabolicMD
VIP Member
2,345
16,789
Jan 2024
Rochester, MN
Mar 7, 2026 at 5:24 AM#1
Unpopular opinion: A1c and fasting glucose are late-stage markers. By the time they're abnormal, you've had insulin resistance for YEARS. The earlier markers — fasting insulin and HOMA-IR — catch metabolic dysfunction way sooner, and almost nobody orders them. Here's why this matters: my fasting glucose was "normal" (96 mg/dL) and my A1c was "normal" (5.5%) when I was already profoundly insulin resistant. My fasting insulin was 32 µIU/mL (normal <25) and my HOMA-IR was 7.6 (normal <2.0). My HOMA-IR journey on semaglutide (12 months): | Month | Fasting Glucose | Fasting Insulin | HOMA-IR | A1c | |-------|----------------|----------------|---------|-----| | 0 | 96 mg/dL | 32.4 µIU/mL | 7.68 | 5.5% | | 3 | 92 | 22.1 | 5.01 | 5.4% | | 6 | 88 | 14.8 | 3.21 | 5.3% | | 9 | 84 | 9.2 | 1.90 | 5.1% | | 12 | 82 | 6.8 | 1.37 | 5.0% | Look at how much the insulin and HOMA-IR moved compared to glucose and A1c. If I'd only been tracking A1c, I would have gone from 5.5 to 5.0 and thought "meh, small change." But the HOMA-IR tells the REAL story: I went from severe insulin resistance to insulin sensitive. That's metabolic transformation. HOMA-IR reference: | HOMA-IR | Interpretation | |---------|---------------| | <1.0 | Optimal insulin sensitivity | | 1.0-1.9 | Normal | | 2.0-2.9 | Early insulin resistance | | 3.0-5.0 | Moderate insulin resistance | | >5.0 | Severe insulin resistance | Get. Your. Fasting. Insulin. Checked. 🔬
37 4SleepDoc_PDX, RegAffairsDC, BiostatsBrad and 34 others
Reply Quote Save Share Report
patPC_UT
Member
212
890
Nov 2024
Park City, UT
Mar 7, 2026 at 5:41 AM#2
you're preaching to the choir. I order fasting insulin and HOMA-IR on virtually every metabolic patient and I'm amazed at how many of my colleagues don't. The reason this matters so much clinically: > By the time fasting glucose exceeds 100 mg/dL, the average patient has had insulin resistance for 8-13 years (Kraft insulin response patterns, University of Michigan data). During those 8-13 years, the pancreas is compensating by producing more and more insulin to keep glucose normal. The beta cells are working overtime. Eventually they burn out → glucose rises → prediabetes → diabetes. Fasting insulin catches this DURING the compensation phase when glucose still looks normal. A fasting glucose of 96 with a fasting insulin of 32 means the pancreas is screaming to maintain normoglycemia. That's not "normal" — that's compensated disease. I also find the Kraft insulin response test (5-hour glucose tolerance test with insulin measurements at 0, 30, 60, 120, 180, 240, 300 min) incredibly informative, though it's rarely done outside research settings.
10 8mike.trainer_LA, sarah_nash92, FitDadDave and 7 others
Reply Quote Save Share Report
Dr.GastroMayo
VIP Member
2,345
13,456
Jan 2024
Mayo Clinic, MN
Mar 7, 2026 at 5:58 AM#3
Okay this thread is scary. I just got my fasting insulin for the first time (thanks to this forum actually) and it came back at 28.6 µIU/mL. My fasting glucose was 102 and A1c 5.7%. HOMA-IR calculation: (28.6 × 102) / 405 = 7.2 So I'm severely insulin resistant according to Rachel's scale, but my A1c is only "prediabetic." My doctor's note literally says "borderline A1c, continue lifestyle modifications." No urgency at all. Should I be pushing harder for treatment? I'm 34 years old, BMI 33.
Last edited: Mar 7, 2026 at 10:58 AM
33 7COA_Karl, MikeFit_NJ, InsuranceTom and 30 others
Reply Quote Save Share Report

Sigma-Aldrich — Research-Grade Standards

Certified reference materials, analytical reagents, and research-grade standards for peptide verification. Trusted by laboratories worldwide.

Shop Reference Standards
andrew_nyc
Member
534
2,345
Apr 2024
New York, NY
Mar 7, 2026 at 6:15 AM#4
you are EXACTLY the type of patient I'm trying to reach with this thread. Your A1c of 5.7 looks borderline and non-urgent. Your HOMA-IR of 7.2 tells a completely different story — your pancreas is working 3-4x harder than normal to keep your glucose barely in range. At 34 with a HOMA-IR of 7.2 and BMI 33, without intervention you are on a near-certain trajectory toward Type 2 diabetes within 5-10 years. The beta cell compensation will eventually fail. I'm not a doctor so I can't tell you what to do, but I would: 1. Share the HOMA-IR data with your doctor explicitly 2. Ask about metformin or GLP-1 therapy as early intervention 3. Dramatically reduce refined carbohydrates and increase protein 4. Start resistance training if you're not already (muscle is an insulin sink) 5. Recheck in 3 months You have a window of opportunity here. Don't let "borderline A1c" lull you into complacency.
4 0julia.endo, JessicaM_2024, TomFromTexas and 1 other
Reply Quote Save Share Report
VendorMark
Senior Member
3,456
14,567
Jan 2024
Texas
Online
Mar 7, 2026 at 6:32 AM#5
the advice above is sound. I want to add that at your age (34), with HOMA-IR >5, the 10-year risk of progression to T2D is approximately 50-70% without intervention (data from the DPP trial and ORIGIN study). The good news: intervention at this stage is HIGHLY effective. The DPP trial showed that intensive lifestyle modification reduced diabetes incidence by 58%. Metformin reduced it by 31%. More recent data suggests GLP-1 RAs may be even more effective for preventing progression. You are at the IDEAL intervention point — insulin resistant but with preserved beta cell function. Your C-peptide (if checked) is likely normal or elevated, meaning your pancreas can still produce insulin. Once beta cells start dying, that's when things become harder to reverse. I'd recommend bringing these numbers to your doctor and framing it as: "I understand my A1c is borderline, but my fasting insulin and HOMA-IR suggest significant insulin resistance. Can we discuss early intervention options?" If they're dismissive, consider seeing an endocrinologist or obesity medicine specialist.
8 0claudia_zurich, nancy_portland, rick_sfbay and 5 others
Reply Quote Save Share Report

Similar Threads

SUSTAIN-6 to SELECT — the cardiovascular evidence timeline14 replies
GLP-1 and insulin resistance — HOMA-IR improvement data17 replies
Metabolic syndrome reversal criteria — how GLP-1 addresses all 55 replies
A1C target achievement rates — sema vs tirz comparison8 replies
SURPASS-CVOT: tirzepatide cardiovascular outcomes trial design3 replies
ForumsNewTrendingMembersAccount

Log In

Forgot password?
No account? Register