What this calculator measures
A standard blood test already contains most of what you need to estimate how well your body handles carbohydrate. Insulin resistance, where cells respond sluggishly to insulin and the pancreas has to push out more of it, usually shows up in triglycerides, HDL, and fasting glucose years before blood sugar crosses into the diabetes range. This tool turns those numbers into the ratios and indexes researchers use, and shows where yours sit relative to published cutoffs.
It is built for one job in particular: measuring a dietary change instead of guessing at it. If you are trying a low-carb, keto, or carnivore diet for a health reason, enter your labs from before you started and your labs from now, and the comparison shows what actually moved. Our guide to low-carb and carnivore diets for chronic disease covers what the research says about each condition and how to run that kind of trial safely.
The markers, one by one
Triglyceride-to-HDL ratio
Divide triglycerides by HDL, both in mg/dL. Insulin resistance tends to push triglycerides up and HDL down at the same time, so the ratio amplifies the signal. McLaughlin and colleagues at Stanford found it was one of the most practical markers for spotting insulin-resistant adults in an overweight population, using a cutoff of 3.0. The ratio is less reliable in some groups, including Black Americans, who often have lower triglycerides even when insulin resistant.
TyG index
The triglyceride-glucose index is ln(triglycerides x fasting glucose / 2), with both values in mg/dL. It was proposed in 2008 as a cheap substitute for insulin testing and has since been studied in large populations. Cutoffs vary by population, from roughly 8.3 to 9.0, so treat the band as context and the trend as the useful part.
HOMA-IR
The homeostasis model assessment combines fasting insulin and fasting glucose: insulin (µIU/mL) x glucose (mg/dL) / 405. It is the most direct of the three, but it needs a fasting insulin test, and insulin assays are not standardized between labs. Studies commonly flag values somewhere between about 2.0 and 2.9. Compare your own results from the same lab rather than chasing a single number.
Glucose and HbA1c
The American Diabetes Association places fasting glucose of 100 to 125 mg/dL and HbA1c of 5.7 to 6.4% in the prediabetes range, and 126 mg/dL or 6.5% and above in the diabetes range. A diagnosis needs confirmation with repeat testing, which is a clinician’s job.
Non-HDL and remnant cholesterol
Non-HDL cholesterol is total cholesterol minus HDL: every cholesterol-carrying particle that can contribute to plaque. Desirable is under 130 mg/dL. Remnant cholesterol is total minus LDL minus HDL. One caution: most standard panels calculate LDL from a formula rather than measuring it, and in that case the remnant figure is derived from your triglycerides and adds little new information.
Metabolic syndrome check
Metabolic syndrome is a cluster of five risk factors defined jointly in 2009 by several international heart and diabetes bodies: a large waist, high triglycerides, low HDL, raised blood pressure, and raised fasting glucose. Any three qualify, and taking medication for one counts as meeting it. Waist cutoffs depend on ancestry, so the calculator lets you choose US/European or Asian thresholds.
How a low-carb diet tends to move these numbers
Carbohydrate restriction has a fairly consistent lab signature. In trials comparing low-carb and low-fat diets in people with metabolic syndrome, the low-carb groups saw larger drops in triglycerides and larger rises in HDL, which shows up here as a falling TG/HDL ratio and TyG index. Fasting insulin and glucose usually come down as well, particularly when weight comes off.
LDL cholesterol does not follow the same script. On very-low-carb and carnivore diets it often rises, and in a minority of lean, active people it rises a lot. Whether that matters in the context of low triglycerides and high HDL is actively debated, and it is not something to settle with a calculator. If your LDL climbs, show the before-and-after numbers to your clinician and decide together. The calculator flags LDL of 190 mg/dL or more because guidelines treat that level as needing a clinical look regardless of diet.
Getting a fair before-and-after
Lab values swing with conditions, so a comparison is only as good as its consistency. Fast for 10 to 12 hours before each draw, avoid a hard workout or heavy drinking the day before, and use the same lab if you can. Retest around three months in, which is long enough for HbA1c to reflect the change. If you take insulin, a sulfonylurea, an SGLT2 inhibitor, or blood pressure medication, talk to your prescriber before cutting carbs, not after: doses often need to come down quickly, and that is their call to make.
Sources
- McLaughlin T, Abbasi F, Cheal K, et al. Use of metabolic markers to identify overweight individuals who are insulin resistant. Ann Intern Med. 2003;139(10):802-809.
- Simental-Mendía LE, Rodríguez-Morán M, Guerrero-Romero F. The product of fasting glucose and triglycerides as surrogate for identifying insulin resistance in apparently healthy subjects. Metab Syndr Relat Disord. 2008;6(4):299-304.
- Matthews DR, Hosker JP, Rudenski AS, et al. Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia. 1985;28(7):412-419.
- Alberti KGMM, Eckel RH, Grundy SM, et al. Harmonizing the metabolic syndrome: a joint interim statement. Circulation. 2009;120(16):1640-1645.
- American Diabetes Association. Standards of Care in Diabetes: Diagnosis and Classification of Diabetes.
- Volek JS, Phinney SD, Forsythe CE, et al. Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet. Lipids. 2009;44(4):297-309.