Normal blood sugar level chart by age

Blood sugar is the amount of glucose circulating in the blood at any given moment.

For most adults without diabetes, it sits below 100 mg/dL (5.6 mmol/L) before eating and rises to under 140 mg/dL (7.8 mmol/L) two hours after a meal.

But “normal” looks different at 8 years old, 38, and 78 – and it changes significantly during pregnancy.

This guide walks through the full chart by age, explains why each range exists, and shows how continuous glucose monitoring (CGM) data can shine a light on your health.

A quick note on units: Two units are used worldwide. mg/dL (milligrams per decilitre) is standard in the US, Japan, France, and parts of Europe. mmol/L (millimoles per litre) is standard in the UK, India, Australia, Canada, and most of the rest of the world. Both numbers appear throughout this guide.

The chart at a glance

Three tests are used to check blood sugar:

• Fasting glucose: Measured after eight or more hours without food, usually first thing in the morning.
• 2-hour OGTT (oral glucose tolerance test): The level two hours after drinking 75 grams of glucose; used to diagnose diabetes.
• A1C: Average blood sugar over the past two to three months; no fasting required.

The American Diabetes Association uses the bands below to label a result as Normal, Prediabetes or Diabetes (American Diabetes Association, Diabetes Care 2026 ).

A diabetes diagnosis usually needs two abnormal results – either two different tests above the threshold, or the same test repeated on a separate day.

Why “by age” matters

The normal range changes with age:

• The body becomes less responsive to insulin with each decade past 40, meaning the same meal raises blood sugar more than it used to
• For older adults, the maths shifts – avoiding dangerous lows from diabetes medication matters more than chasing complications that take decades to develop
• Pregnancy and childhood each have their own targets – a fasting number that’s reassuring in a 30-year-old can be a warning sign in a pregnant woman

The sections below walk through each life stage.

Children and adolescents

For children without diabetes, the diagnostic thresholds match adults: fasting under 100 mg/dL (5.6 mmol/L), 2-hour OGTT under 140 mg/dL (7.8 mmol/L).

For children with type 1 diabetes (the most common form in kids), the ADA recommends (ADA Standards of Care, Chapter 14, Diabetes Care 2026 ):

• A1C: under 7.0%
• Before meals: 70–130 mg/dL (3.9–7.2 mmol/L)
• At bedtime: 80–140 mg/dL (4.4–7.8 mmol/L)

Targets are adjusted child by child. For kids who can’t easily feel when their blood sugar is dropping low (a condition called hypoglycaemia unawareness), or whose family setup makes tight management harder, the care team may loosen the A1C goal to under 7.5%. Continuous glucose monitoring is now standard care for paediatric type 1 diabetes – it cuts the risk of severe lows without sacrificing average control.

Adults without diabetes

• A fasting glucose of 85–99 mg/dL (4.7–5.5 mmol/L) is in the normal range; the upper end of that band is worth tracking year-over-year if it’s trending upward
• An occasional post-meal reading above 140 mg/dL (7.8 mmol/L) can occur even in healthy adults. CGM studies show meaningful day-to-day variability in non-diabetic glucose curves (Hall H et al., PLoS Biology 2018 ). It’s the pattern over time, not one high number, that matters
• An A1C between 5.3 and 5.6% is normal; 5.7% and above enters the prediabetes band

For more on what an A1C means in mg/dL or mmol/L, see the Ultrahuman A1C calculator guide.

Adults with diabetes

For adults already diagnosed with type 1 or type 2 diabetes, the ADA’s day-to-day targets are (ADA Standards of Care, Chapter 6, Diabetes Care 2026 ):

• Before meals: 80–130 mg/dL (4.4–7.2 mmol/L)
• Peak after meals (1–2 hours later): under 180 mg/dL (under 10.0 mmol/L)
• A1C: under 7.0% for most adults

A doctor may tighten or loosen these. Younger adults without other health problems may aim for an A1C under 6.5%; adults with multiple conditions or shorter life expectancy may aim for under 8.0%. The goal is balancing two risks – the long-term complications of high blood sugar against the immediate danger of going too low from diabetes medication.

Older adults (65+)

Older adults aren’t one group. For older adults with diabetes, the ADA splits them into three tiers based on overall health, with a different target for each. (For older adults without diabetes, the normal-prediabetes-diabetes bands in the master chart above still apply.) The framework (ADA Standards of Care, Chapter 13, Diabetes Care 2026 ):

Pregnancy

Pregnancy is the one life stage when blood sugar targets are tighter, not looser. High blood sugar during pregnancy raises the risk of a larger-than-average baby (called large-for-gestational-age), preeclampsia (dangerous high blood pressure during pregnancy), and the newborn having low blood sugar after birth. The HAPO study found these risks rise continuously with maternal blood sugar – there’s no specific number below which risk drops to zero (HAPO Study Cooperative Research Group, New England Journal of Medicine 2008 ).

For pregnant women with diabetes (pre-existing type 1, type 2, or pregnancy-induced), the ADA targets are (ADA Standards of Care, Chapter 15, Diabetes Care 2026 ):

• Fasting: under 95 mg/dL (under 5.3 mmol/L)
• 1 hour after a meal: under 140 mg/dL (under 7.8 mmol/L)
• 2 hours after a meal: under 120 mg/dL (under 6.7 mmol/L)
• A1C: under 6.0–6.5%, set with the obstetric team

Gestational diabetes is diabetes that develops during pregnancy. It’s screened with a 75-gram OGTT between weeks 24 and 28. Any one of these results at or above threshold is enough for the diagnosis (IADPSG Consensus Panel, Diabetes Care 2010 ):

• Fasting: ≥ 92 mg/dL (≥ 5.1 mmol/L)
• 1 hour: ≥ 180 mg/dL (≥ 10.0 mmol/L)
• 2 hour: ≥ 153 mg/dL (≥ 8.5 mmol/L)

Any pregnant woman with concerns should follow the obstetric team’s testing schedule rather than self-screening against these numbers.

Time-in-range

A fasting number, a post-meal number, and an A1C are three snapshots. All three can sit in the normal band while blood sugar is actually swinging widely throughout the day. CGM data fills that gap.

Time-in-Range (TIR) is the percentage of the day spent inside a target glucose range. For most people with diabetes, the range is 70–180 mg/dL (3.9–10.0 mmol/L). The more time spent inside the range, the better the day-to-day control. An international group of diabetes experts set the following TIR targets (Battelino T et al., Diabetes Care 2019 ):

For adults without diabetes, CGM data shows what a single lab test cannot – how steady (or jumpy) the day-to-day glucose curve actually is, which foods spike it, and how sleep, stress, and exercise reshape the response. An Ultrahuman M2 Live CGM makes this visible day to day, rather than waiting for a quarterly lab. In a study Ultrahuman published in Scientific Reports in 2024, M1 CGM data across 14 days showed measurable differences in mean glucose, time spent in the tighter 70–110 mg/dL (3.9–6.1 mmol/L) range, and glucose variability between non-diabetic and pre-diabetic adults (N=105; Chaudhry M et al., Scientific Reports 2024 ) – differences a one-off lab test would have missed.

What shifts blood sugar numbers

Four levers move blood sugar quickly:

• Food choice and order. Eating fibre, protein, and fat before the carb portion of a meal flattens the post-meal spike noticeably (Shukla AP et al., Diabetes Care 2015 )
• Movement after meals. A 10–15 minute walk after eating shuttles glucose into the muscles before insulin has to clear it (Reynolds AN et al., Diabetologia 2016 )
• Sleep. A single short or fragmented night raises fasting glucose the next morning (Donga E et al., Journal of Clinical Endocrinology & Metabolism 2010 ); chronic poor sleep nudges A1C up over months
• Stress. Cortisol – the main stress hormone – raises blood sugar. Long stretches of stress can lift fasting numbers without any change in diet

For a deeper walkthrough on moving these numbers, see the Ultrahuman guide on lowering A1C naturally. For the broader picture of what a reading means and how to interpret it, see the ultimate guide to blood glucose levels.

When to talk to a healthcare provider

Talk to a provider if:

• Fasting glucose is 100 mg/dL (5.6 mmol/L) or higher on two separate days – confirm with a lab test
• A random or post-meal reading is 200 mg/dL (11.1 mmol/L) or higher, especially with thirst, frequent urination, or unexplained weight loss
• A1C is 5.7% or higher – the prediabetes band is where lifestyle changes have the biggest payoff
• Pregnant – the obstetric team will set the glucose-testing schedule, including a formal gestational diabetes screening between weeks 24 and 28; the thresholds in this article aren’t for self-screening
• On diabetes medication and seeing frequent lows (under 70 mg/dL or 3.9 mmol/L) – the dose may need adjusting

Frequently asked questions

What is a normal blood sugar level by age? For non-diabetic adults, fasting glucose sits below 100 mg/dL (5.6 mmol/L) and post-meal readings below 140 mg/dL (7.8 mmol/L) across all ages. The diagnostic bands are the same at 25 and 75. What shifts with age is how tightly the targets are set for people already living with diabetes, and the medication risks that go with tight control in older adults.

What blood sugar level is considered diabetic? Fasting glucose at or above 126 mg/dL (7.0 mmol/L), a 2-hour OGTT at or above 200 mg/dL (11.1 mmol/L), or an A1C at or above 6.5%. Two abnormal results are usually required for a diagnosis – either two different tests, or the same test on separate days.

What is a normal blood sugar level for a child? The diagnostic thresholds match adults: fasting under 100 mg/dL (5.6 mmol/L), 2-hour OGTT under 140 mg/dL (7.8 mmol/L). For children already living with type 1 diabetes, the ADA target is an A1C under 7.0%, with individual adjustments where hypoglycaemia awareness or family circumstances make tight control harder.

What is a normal blood sugar level during pregnancy? Pregnancy tightens the targets. For a pregnant woman with pre-existing or gestational diabetes, the ADA aims for fasting under 95 mg/dL (5.3 mmol/L), under 140 mg/dL (7.8 mmol/L) one hour after a meal, and under 120 mg/dL (6.7 mmol/L) two hours after. The obstetric team sets the personal target.

What is a good blood sugar for an older adult? It depends on overall health. The ADA sets three tiers: healthy older adults aim for A1C under 7.0–7.5%, those with multiple conditions under 8.0%, and those with advanced illness or frailty under 8.5%. The targets relax to reduce the risk of dangerous lows from diabetes medication.

Why is my fasting glucose higher than my post-meal? Usually the dawn phenomenon – a natural early-morning rise driven by cortisol and growth hormone as the body prepares to wake. A high fasting reading with normal post-meal readings suggests overnight hormonal activity rather than a food problem. Persistent high fasting numbers still warrant a lab test.

Can blood sugar chart numbers be wrong? A single home reading can be misleading – finger-prick meters have a margin of error of around 10–15%, and lab results can be affected by recent food, illness, or stress. The pattern across multiple readings and multiple tests is what matters. A single high number isn’t a diagnosis.

This article is for informational purposes and isn’t medical advice. People with diabetes or suspected metabolic conditions should work with a clinician for diagnosis, medication, and treatment decisions. Disclosure: Ultrahuman sells the M2 Live CGM, Ring AIR and Ring PRO referenced in this guide.