A fasting blood glucose of 113 mg/dL sits above the normal cutoff of 99 mg/dL and squarely within the range most medical organizations label “prediabetes,” which spans 100 to 125 mg/dL. It is not diabetes, which starts at 126 mg/dL on two separate fasting tests, but it is a signal your body is having a harder time keeping blood sugar in check. Whether this reading calls for immediate concern depends on context: how the blood was drawn, what you ate and did beforehand, and whether the result is a one-off or a pattern.
Where 113 Falls on the Diagnostic Spectrum
Medical guidelines split fasting blood glucose into three broad zones. Below 100 mg/dL is considered normal. Between 100 and 125 mg/dL is classified as impaired fasting glucose, the fasting-glucose version of prediabetes. At 126 mg/dL or higher on two separate occasions, the diagnosis shifts to type 2 diabetes. Your reading of 113 mg/dL lands in the upper half of that middle zone, closer to the diabetes threshold than to normal.
The prediabetes category itself is not universally drawn at the same lines. The American Diabetes Association uses the 100–125 mg/dL range, while the World Health Organization sets the lower boundary at 110 mg/dL. Under the WHO definition, a reading of 113 would still qualify as impaired fasting glucose, but just barely. These differing cutoffs reflect ongoing debate about where “mildly elevated” ends and “meaningfully risky” begins. Regardless of which organization’s criteria your doctor follows, 113 mg/dL is above the point where everyone agrees glucose metabolism is working normally.1World Journal of Diabetes. Prediabetes diagnosis and treatment: A review
Why One Reading Might Not Tell the Full Story
Fasting glucose is not as rock-solid as it might seem. In people with newly diagnosed type 2 diabetes, fasting glucose varied by roughly 15% from one day to the next, and most of that swing was biological rather than caused by lab error.2PubMed Central. Day-to-day variability of fasting plasma glucose in newly diagnosed type 2 diabetic subjects That means a person whose “true” average fasting glucose is 105 mg/dL could easily produce a 113 reading one morning and a 97 the next. One reading in the prediabetes zone does not automatically mean you have prediabetes; your doctor will almost certainly want to repeat the test or follow up with a hemoglobin A1c measurement before drawing conclusions.
The device used to measure your blood matters, too. If you tested at home with a fingerstick glucometer rather than at a lab, there is additional room for error. A long-term comparison of home glucose monitors and lab-grade venous blood tests found an average gap of about 11 mg/dL between the two, with some individual readings off by more than 50 mg/dL.3PubMed Central. Comparing Self Monitoring Blood Glucose Devices and Laboratory Tests: Over 25 Years Experience A separate evaluation of a commonly used glucometer found it consistently underestimated blood glucose by about 3 mg/dL on average, but the range of disagreement stretched quite wide.4PubMed Central. Evaluation of the accuracy, precision, and agreement of a glucometer compared to the standard laboratory test in diabetic and non-diabetic patients If your 113 came from a fingerstick meter, a lab draw could return a somewhat different number in either direction.
The Dawn Phenomenon and Morning Readings
If you measured first thing in the morning, a natural hormonal process may have nudged your glucose higher than it was during the night. In the hours before waking, your body releases cortisol and growth hormone to prepare you for the day, and these hormones prompt the liver to dump glucose into the bloodstream. This is called the dawn phenomenon. In people with type 2 diabetes, the median rise from the overnight low point to the pre-breakfast reading was about 16 mg/dL, and for some individuals it was over 30 mg/dL.5PubMed Central. Magnitude of the dawn phenomenon and its impact on the overall glucose exposure in type 2 diabetes The dawn effect also occurs in people without diabetes, though usually to a smaller degree. If your glucose was sitting comfortably in the 90s at 3 a.m. and you measured at 7 a.m., some of that 113 may be your morning hormone surge rather than a sign of all-day glucose trouble.
Stress, Sleep, and Medications Can Push Glucose Up
A fasting glucose reading is a snapshot, and several temporary factors can raise that snapshot without reflecting a chronic metabolic problem. Psychological stress is one of the big ones. When you are anxious or under pressure, your body releases stress hormones like cortisol and adrenaline, both of which increase insulin resistance and prompt the liver to release stored glucose.6PubMed Central. Stress-Induced Diabetes: A Review A bad night of sleep before a fasting blood test, a stressful morning commute to the lab, or an unusually anxious week at work can all translate into a higher number on the screen.
Sleep itself plays a role. Short or disrupted sleep has been linked to impaired fasting glucose, and the effect can be particularly pronounced in people who work irregular shifts. In one study of shift workers, men who got insufficient sleep had roughly three times the odds of having impaired fasting glucose compared to those who slept enough.7PubMed Central. Association between sleep duration and impaired fasting glucose according to work type in non-regular workers If your reading of 113 coincided with a stretch of poor sleep, that is worth mentioning to your doctor.
Certain medications can also raise fasting glucose. Corticosteroids like prednisone are well-known offenders, but the list extends to some blood-pressure medications, antipsychotics, and immunosuppressants.8PubMed Central. Medication-Induced Hyperglycemia and Diabetes Mellitus: A Review of Current Literature and Practical Management Strategies If you recently started or changed a medication and your glucose crept up, the drug rather than your diet might be the primary driver.
What Prediabetes Means for Long-Term Health
If repeat testing confirms that 113 reflects your usual fasting glucose, the prediabetes label carries real implications. A large meta-analysis found that people with prediabetes had about a 13% higher risk of dying from any cause and a 15% higher risk of cardiovascular disease over a median follow-up of nearly ten years, compared with people whose blood sugar was normal.9BMJ. Association between prediabetes and risk of all cause mortality and cardiovascular disease: updated meta-analysis The risk of heart failure also rises; depending on how prediabetes was defined, the increase ranged from about 9% to nearly 60%.10Diabetes, Obesity and Metabolism. Prediabetes and the risk of heart failure: A meta-analysis
One especially important finding is that these risks do not simply vanish if you never go on to develop full diabetes. A recent study tracked people with prediabetes and found that even after accounting for those who progressed to diabetes, roughly 85% of the excess risk for complications remained. In other words, prediabetes itself, not just the possibility of future diabetes, was associated with elevated risks of cardiovascular disease, heart failure, kidney disease, and death.11PubMed Central. Prediabetes is associated with elevated risk of clinical outcomes even without progression to diabetes That makes a reading of 113 worth taking seriously even if you never cross the 126 threshold.
How Likely Is It to Become Diabetes?
Prediabetes does not inevitably progress to diabetes, and for many people it never does. A large pooled analysis of individual-level data found that within ten years, about 12.5% of people with prediabetes went on to develop type 2 diabetes, while roughly 36% reverted to normal glucose levels. The rest stayed somewhere in the prediabetes range.12The Lancet. Global rates of and risk factors for prediabetes transitions to type 2 diabetes or normoglycaemia: a pooled analysis of individual-level data That said, the odds of progression climbed steeply for people in the highest fasting-glucose quartile. Since 113 mg/dL sits in the upper half of the prediabetes band, your personal odds of progression are higher than the average figure for all people with prediabetes.
Over a lifetime, the picture is less reassuring. One study estimated that a 45-year-old woman with ADA-defined prediabetes had about a 58% lifetime risk of eventually developing overt diabetes, and a 45-year-old man had about a 46% lifetime risk.13BMJ Open Diabetes Research & Care. Lifetime risk to progress from pre-diabetes to type 2 diabetes among women and men These numbers underscore that while ten-year conversion rates look modest, prediabetes often persists for decades, and each year it lingers adds more cumulative risk.
Several factors tilt the odds toward progression. A systematic review and meta-analysis identified family history of diabetes, higher BMI, larger waist circumference, lack of physical activity, smoking, hypertension, elevated triglycerides, and fatty liver as the strongest predictors of moving from prediabetes to diabetes.14PubMed Central. Risk factors for progression to type 2 diabetes in prediabetes: a systematic review and meta-analysis If you carry several of these risk factors alongside a fasting glucose of 113, the urgency to act is higher than if 113 is your only red flag.
Why Your Doctor Will Probably Order an A1c
Fasting glucose captures what is happening at one moment. Hemoglobin A1c provides a broader view by reflecting your average blood sugar over the past two to three months. An A1c below 5.7% is considered normal, 5.7% to 6.4% maps to prediabetes, and 6.5% or above indicates diabetes. If your fasting glucose is 113, your doctor will likely want an A1c to see whether that elevated reading is a fluke or part of a sustained trend.
The relationship between a single fasting glucose value and A1c is imperfect. Research shows that A1c correlates with any single glucose measurement, but the correlation improves when you have multiple readings, especially from the month before the A1c was drawn.15PubMed Central. The correlation of hemoglobin A1c to blood glucose Fasting glucose in particular tends to underestimate the average glucose level that A1c reflects, and this gap widens as A1c rises. Post-meal glucose readings and bedtime readings correlate with A1c more closely than fasting glucose does.16National Glycohemoglobin Standardization Program. HbA1c and Estimated Average Glucose In practical terms, this means that if your fasting glucose is 113 but your after-meal spikes run noticeably higher, your A1c could come back more elevated than the fasting number alone would suggest.
Post-Meal Walking and Other Practical Steps
The encouraging news about prediabetes is that it responds well to lifestyle changes, sometimes dramatically. One of the simplest interventions with solid evidence behind it is a short walk after eating. A study measuring post-meal glucose found that a brisk ten-minute walk taken immediately after a glucose load lowered the two-hour glucose area significantly compared to sitting still, and it also blunted the peak glucose spike by about 18 mg/dL on average.17PubMed Central. Positive impact of a 10-min walk immediately after glucose intake on postprandial glucose levels Separate research in older adults at risk for impaired glucose tolerance found that three 15-minute walks after meals significantly improved 24-hour glucose control, with the largest benefit occurring after dinner.18Diabetes Care. Three 15-min Bouts of Moderate Postmeal Walking Significantly Improves 24-h Glycemic Control in Older People at Risk for Impaired Glucose Tolerance You do not need a gym membership or a complex exercise plan. Walking a few minutes after each meal is one of the most effective and accessible things you can do.
Dietary changes also make a measurable difference. In a study of adults with type 2 diabetes who switched to a low-carbohydrate diet, fasting blood sugar dropped by about 14 mg/dL after three months and remained lower at six months.19PubMed Central. Comprehensive analysis of systemic, metabolic, and molecular changes following prospective change to low-carbohydrate diet in adults with type 2 diabetes mellitus in India While that study was in people who already had diabetes rather than prediabetes, a 14-point drop applied to a fasting glucose of 113 would bring the reading back to 99, which is normal territory. You do not necessarily need to go low-carb specifically; reducing refined carbohydrates, sugary drinks, and processed foods while increasing fiber and whole foods produces similar directional effects across a range of dietary patterns.
Intermittent fasting has also attracted attention. A systematic review and meta-analysis found that fasting regimens lowered fasting blood glucose and reduced insulin resistance in people with metabolic syndrome and glucose intolerance.20BMC. The effect of intermittent fasting on insulin resistance, lipid profile, and inflammation on metabolic syndrome Whether any particular fasting schedule is better than simply eating less overall is still debated, but for some people the structure of a defined eating window makes it easier to stick with calorie reduction and carbohydrate moderation.
When Pregnancy Changes the Thresholds
If you are pregnant or trying to conceive, the interpretive framework for blood glucose shifts. Gestational diabetes is diagnosed using an oral glucose tolerance test rather than a simple fasting glucose, and the fasting cutoff used for that test is typically 92 mg/dL under the criteria recommended by the International Association for Diabetes in Pregnancy Study Groups.21PubMed. Association between number of abnormal glucose values and severity of fasting plasma glucose in IADPSG criteria and maternal outcomes in women with gestational diabetes mellitus Under those criteria, a fasting glucose of 113 mg/dL during pregnancy would already exceed the gestational diabetes threshold. Pregnant individuals with a number like this should expect their provider to move quickly toward a management plan rather than taking a wait-and-see approach.
What Continuous Glucose Monitors Reveal in People Without Diabetes
The rise of continuous glucose monitors has given researchers and consumers a much more detailed picture of glucose fluctuations throughout the day. A large-scale mapping of CGM data from over 7,000 non-diabetic adults found that blood sugar in healthy people is far from flat. It spikes after meals, dips during physical activity, and varies from hour to hour in ways a single fasting reading cannot capture.22PubMed. CGMap: Characterizing continuous glucose monitor data in thousands of non-diabetic individuals Some otherwise healthy people regularly see post-meal readings in the 140s or even 160s before their insulin catches up and pulls glucose back down. A fasting value of 113 in a person whose glucose spends most of the day in the 90s and 100s tells a different story than 113 in someone who is also spiking to 180 after every meal. If you are considering getting a fuller picture of your glucose patterns, CGMs can be a useful complement to traditional lab work, though they are not yet standard of care for people without diabetes.
The existence of these data also highlights a common misconception: that glucose regulation is a binary switch that is either “working” or “broken.” In reality, insulin sensitivity exists on a spectrum, and a fasting glucose of 113 means your body is somewhere in the middle of that spectrum, still compensating but working harder than it should have to. The pancreas may still be producing plenty of insulin, but the cells are responding to it less efficiently. This is the stage where lifestyle changes have the most leverage, because the system is strained but not yet exhausted.