Skip to content
How It Works
Explore
Ask a Question Resources Pricing
Who It's For
Patients
Decode results, prep for appointments, weigh options.
Caregivers & advocates
Carry the research load for someone you love.
Providers & clinicians
Resources for patients in your practice.
Log In Ask a Question
PubMed This is a summary of 18 peer-reviewed journal articles Updated
Endocrinology · Prediabetes

The Biology of Prediabetes and Your Risk Profile

At a Glance

Prediabetes reflects insulin resistance and reduced ability of pancreatic beta cells to make enough insulin. Risk of type 2 diabetes is higher when fasting and after-meal glucose problems occur together or when abdominal fat, fatty liver risk, high triglycerides, or family history are present.

Prediabetes is not a single, uniform condition. It is a metabolic state driven by two primary biological “engines”: insulin resistance and beta-cell dysfunction [1]. Understanding which engine is driving your numbers—and where in your body the resistance is strongest—helps your doctor determine your specific risk profile.

The Biological Drivers: Resistance and Failure

To understand prediabetes, it helps to think of your body’s glucose management as a supply-and-demand system:

  • Insulin Resistance: This occurs when your muscles, fat, and liver stop responding effectively to insulin, the hormone that unlocks your cells to let sugar in [2]. Because the “locks” are jammed, your body must produce more and more insulin to get the same result.
  • Beta-Cell Dysfunction: Beta cells are the specialized cells in your pancreas that produce insulin [3]. In the early stages of prediabetes, these cells work overtime to compensate for resistance. Prediabetes progresses toward type 2 diabetes when these cells begin to “tire out” or fail, and they can no longer produce enough insulin to overcome the resistance [1][4].

The Two Subtypes: IFG vs. IGT

Doctors categorize prediabetes into two main “flavors” based on which test is abnormal. These represent different biological problems in different parts of the body, though they overlap significantly in practice:

Feature Impaired Fasting Glucose (IFG) Impaired Glucose Tolerance (IGT)
Primary Test Fasting Plasma Glucose (100–125 mg/dL) [5] 2-Hour Oral Glucose Tolerance Test (140–199 mg/dL) [5]
Main Location Hepatic Insulin Resistance (Tends to be associated with the liver releasing too much sugar while you sleep) [6] Muscle Insulin Resistance (Tends to be associated with muscles struggling to clear sugar after a meal) [6]
Cell Problem Impaired “basal” insulin secretion [7] Impaired “early-phase” insulin secretion (a slow response to food) [8]

While both increase your risk, they aren’t the same. For example, some studies suggest that Impaired Glucose Tolerance (IGT) may progress to diabetes faster than IFG alone [9][10].

Identifying the High-Risk Profile

Your doctor assesses your risk of progression by looking for specific “red flags” in your biology.

1. The “Double Hit”: Combined IFG and IGT

The highest risk occurs when a patient has both IFG and IGT simultaneously. This “combined” phenotype means the body is struggling both to regulate sugar overnight and to clear it after meals [11]. One large study found that people with both abnormalities were more than twice as likely to progress to type 2 diabetes compared to those with only one [11]. In some meta-analyses, the relative risk for this combined group is nearly 12 times higher than for people with normal glucose [12].

2. The Role of the Liver (Fatty Liver Index)

A critical driver of prediabetes progression is ectopic fat, or fat stored in places it doesn’t belong—specifically the liver [2]. Doctors sometimes use a tool called the Fatty Liver Index (FLI) to estimate this risk. The FLI is a score from 0 to 100 calculated using your BMI, waist circumference, triglycerides, and a liver enzyme called GGT [13]. It is an estimate, not a diagnosis, and should be evaluated by a clinician.

A high FLI score is a powerful predictor of progression:

  • A score of 60 or higher suggests a higher likelihood of fatty liver [13].
  • In one major study, people with a high FLI score (>60) had higher odds (an odds ratio of 4.5 to 6.8) of developing type 2 diabetes than those with a low score [14][15].
  • A high FLI also makes it less likely that your prediabetes will “revert” back to normal on its own [16].

3. Other Clinical Accelerators

Beyond your blood sugar numbers, several factors act as “accelerators” for the disease:

  • Central Adiposity: Excess weight carried specifically around the abdomen (measured by waist circumference) is more metabolically active and more likely to drive insulin resistance than weight carried elsewhere [11][17].
  • Age and Genetics: A family history of diabetes can mean your beta cells are genetically predisposed to wear out sooner [3][18].
  • Metabolic Markers: High triglycerides and low HDL (“good”) cholesterol often signal that the body’s fat-storage systems are overwhelmed, further fueling the cycle of resistance [11].

Common questions in this guide

How are impaired fasting glucose and impaired glucose tolerance different?
Impaired fasting glucose is usually identified when fasting plasma glucose is 100–125 mg/dL. Impaired glucose tolerance is identified when the two-hour oral glucose tolerance test is 140–199 mg/dL. These patterns can reflect different problems with glucose control, and some people have both.
Is my risk higher if I have both IFG and IGT?
Having both impaired fasting glucose and impaired glucose tolerance means your body has difficulty controlling glucose both between meals and after eating. This combined pattern is associated with a higher chance of developing type 2 diabetes than either abnormality alone. Ask your clinician how this result should affect monitoring and care.
What does a high Fatty Liver Index mean for prediabetes?
The Fatty Liver Index is a score from 0 to 100 estimated from body mass index, waist circumference, triglycerides, and the liver enzyme GGT. A score of 60 or higher suggests a greater likelihood of fatty liver and is associated with a higher chance of progressing to type 2 diabetes. The score estimates risk and does not diagnose fatty liver.
How do insulin resistance and beta-cell problems cause prediabetes?
Insulin resistance means that muscle, fat, and liver cells do not respond well to insulin, so the body needs to make more of it. Pancreatic beta cells may initially increase insulin production, but if they cannot keep up, blood glucose rises and prediabetes can develop or progress.
What factors can make prediabetes progress to type 2 diabetes?
Higher-risk features include having both impaired fasting glucose and impaired glucose tolerance, excess abdominal fat, a family history of diabetes, older age, high triglycerides, low HDL cholesterol, and fatty liver risk. Poor sleep and other lifestyle patterns may also affect how the body processes glucose. Your clinician can help interpret these factors together rather than relying on one result.
Can sleep, activity, and diet affect my prediabetes risk profile?
Diet, physical activity, alcohol habits, and sleep are useful areas to review with your clinician when assessing metabolic and liver health. Poor sleep can affect how the body processes glucose, while waist size, weight, blood pressure, and cholesterol can influence the overall care plan. Ask which changes are safe and most appropriate for your health history.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Based on my results, do I tend to show more fasting glucose issues, post-meal issues, or a combination of both?
  2. 2.Are my triglyceride and GGT levels high enough that we should discuss a clinical assessment for fatty liver?
  3. 3.What specific risk factors do I have (like family history or central adiposity) that might accelerate my progression?
  4. 4.How does my overall cardiometabolic profile (blood pressure, cholesterol, weight) impact my specific treatment plan?
  5. 5.Given my specific health history, what kind of physical activity might be most effective and safe for me?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (18)
  1. 1

    Differential role of insulin resistance and β-cell function in the development of prediabetes and diabetes in middle-aged and elderly Chinese population.

    Cai X, Xia L, Pan Y, et al.

    Diabetology & metabolic syndrome 2019; (11()):24 doi:10.1186/s13098-019-0418-x.

    PMID: 30873220
  2. 2

    Insulin resistance in adipose tissue and fatty liver, but not fat mass, are involved in worsening glycaemic status: The Hiroshima study on glucose metabolism and cardiovascular diseases.

    Sasaki N, Ueno Y, Ozono R, et al.

    Diabetes, obesity & metabolism 2025; (27(6)):3025-3035 doi:10.1111/dom.16307.

    PMID: 40045548
  3. 3

    The PERSonalized Glucose Optimization Through Nutritional Intervention (PERSON) Study: Rationale, Design and Preliminary Screening Results.

    Gijbels A, Trouwborst I, Jardon KM, et al.

    Frontiers in nutrition 2021; (8()):694568 doi:10.3389/fnut.2021.694568.

    PMID: 34277687
  4. 4

    Altered GIP/GLP-1 Secretion Ratio is Associated With Impaired β Cell Function in Humans.

    Di Giuseppe G, Gliozzo G, Ciccarelli G, et al.

    The Journal of clinical endocrinology and metabolism 2025; (111(1)):e240-e246 doi:10.1210/clinem/dgaf210.

    PMID: 40354158
  5. 5

    Is adherence to the alternate healthy eating index an effective approach for prediabetes reversion? A longitudinal follow-up.

    Bahadoran Z, Mirmiran P, Azizi F

    Clinical nutrition ESPEN 2025; (68()):548-556 doi:10.1016/j.clnesp.2025.05.046.

    PMID: 40480463
  6. 6

    A Narrative Review of Human Clinical Trials on the Impact of Phenolic-Rich Plant Extracts on Prediabetes and Its Subgroups.

    Lim WXJ, Gammon CS, von Hurst P, et al.

    Nutrients 2021; (13(11)) doi:10.3390/nu13113733.

    PMID: 34835989
  7. 7

    Insulin Secretory Defect and Insulin Resistance in Isolated Impaired Fasting Glucose and Isolated Impaired Glucose Tolerance.

    Aoyama-Sasabe S, Fukushima M, Xin X, et al.

    Journal of diabetes research 2016; (2016()):1298601 doi:10.1155/2016/1298601.

    PMID: 26788515
  8. 8

    Changes in β-Cell Function in Offspring of Type-2 Diabetic Patients, as per Fasting and Two-Hour Plasma Glucose Levels.

    Praveen EP, Chouhan S, Sahoo J, et al.

    Cureus 2021; (13(5)):e15056 doi:10.7759/cureus.15056.

    PMID: 34017668
  9. 9

    Natural History of Type 2 Diabetes in Indians: Time to Progression.

    Narayan KMV, Kondal D, Chang HH, et al.

    Diabetes care 2024; (47(5)):858-863 doi:10.2337/dc23-1514.

    PMID: 38427346
  10. 10

    Differential effect of nonpharmacological interventions according to prediabetes phenotype: Systematic review and meta-analysis of randomized clinical trials.

    Zila-Velasque JP, Carrillo-Larco RM, Bernabe-Ortiz A

    Diabetic medicine : a journal of the British Diabetic Association 2025; (42(5)):e15511 doi:10.1111/dme.15511.

    PMID: 39815377
  11. 11

    Incidence and predictors of type 2 diabetes among Koreans: A 12-year follow up of the Korean Genome and Epidemiology Study.

    Han SJ, Kim HJ, Kim DJ, et al.

    Diabetes research and clinical practice 2017; (123()):173-180 doi:10.1016/j.diabres.2016.10.004.

    PMID: 28043048
  12. 12

    Evidence From a Systematic Review and Meta-Analysis: Classical Impaired Glucose Tolerance Should Be Divided Into Subgroups of Isolated Impaired Glucose Tolerance and Impaired Glucose Tolerance Combined With Impaired Fasting Glucose, According to the Risk of Progression to Diabetes.

    Liu Y, Li J, Wu Y, et al.

    Frontiers in endocrinology 2022; (13()):835460 doi:10.3389/fendo.2022.835460.

    PMID: 35250886
  13. 13

    A community-based study on the application of fatty liver index in screening subjects with nonalcoholic fatty liver disease.

    Chen LW, Huang PR, Chien CH, et al.

    Journal of the Formosan Medical Association = Taiwan yi zhi 2020; (119(1 Pt 1)):173-181 doi:10.1016/j.jfma.2019.03.016.

    PMID: 30981560
  14. 14

    Fatty liver index is a predictor of incident diabetes in patients with prediabetes: The PREDAPS study.

    Franch-Nadal J, Caballeria L, Mata-Cases M, et al.

    PloS one 2018; (13(6)):e0198327 doi:10.1371/journal.pone.0198327.

    PMID: 29856820
  15. 15

    Fatty liver index and progression to type 2 diabetes: a 5-year longitudinal study in Spanish workers with pre-diabetes.

    Busquets-Cortés C, Bennasar-Veny M, López-González AA, et al.

    BMJ open 2021; (11(8)):e045498 doi:10.1136/bmjopen-2020-045498.

    PMID: 34433590
  16. 16

    Fatty liver index is a strong predictor of changes in glycemic status in people with prediabetes: The IT-DIAB study.

    Wargny M, Smati S, Pichelin M, et al.

    PloS one 2019; (14(8)):e0221524 doi:10.1371/journal.pone.0221524.

    PMID: 31465427
  17. 17

    Prediabetes in Transition: Insights from the Tehran Lipid and Glucose Study.

    Bahadoran Z, Hosseinpanah F

    International journal of endocrinology and metabolism 2025; (23(4)):e166455 doi:10.5812/ijem-166455.

    PMID: 41716863
  18. 18

    Are the determinants of the progression to type 2 diabetes and regression to normoglycemia in the populations with pre-diabetes the same?

    Alizadeh Z, Baradaran HR, Kohansal K, et al.

    Frontiers in endocrinology 2022; (13()):1041808 doi:10.3389/fendo.2022.1041808.

    PMID: 36277718

This page explains biological drivers and risk markers for prediabetes for informational purposes only. It does not constitute medical advice; ask your healthcare professional to interpret your glucose, liver, and lipid results and recommend care.

Get notified when new evidence is published on prediabetes syndrome.

We monitor PubMed for new peer-reviewed studies on this topic and email a short summary when something meaningful changes.