Blood Glucose Thresholds
SugarCalc isn’t just another widget. It’s a robust, medically-focused tool designed to add genuine value to your health or diabetes website.
SugarCalc: Updated Blood Sugar Targets for 2026
We have updated the blood sugar targets in SugarCalc. Medical guidelines change as doctors learn more about diabetes, and we want to make sure SugarCalc always gives you the most accurate advice.
We based these changes on the latest advice from the American Diabetes Association and the UK's National Institute for Health and Care Excellence.
What has changed?
The biggest change is how we warn you about Diabetic Ketoacidosis. This is a serious condition that happens when your blood sugar stays too high for too long.
In the past, doctors thought this only happened when blood sugar reached 15.0 mmol/L. New research shows it can happen at lower levels. We have lowered our warning level to 11.1 mmol/L. If your reading goes above this number, SugarCalc will advise you to check for ketones and seek medical help if you feel unwell. This change helps keep you safe by warning you earlier.
We have also adjusted the daily targets for Type 1 diabetes. The old targets were very strict. This meant the app sometimes warned people when their blood sugar was actually fine. We have widened the targets slightly to match what doctors now recommend.
For example, the fasting target for Type 1 is now 4.0 to 7.0 mmol/L. The target for one to two hours after eating is now 5.0 to 9.0 mmol/L. This means you will see fewer unnecessary warnings.
The targets for Type 2 diabetes remain mostly the same. They already matched the latest medical advice. The fasting target is 4.0 to 7.2 mmol/L, and the after-meal target is 5.0 to 10.0 mmol/L.
We made these updates to give you peace of mind. You can trust that SugarCalc uses the same numbers your doctor uses.
SugarCalc Blood Glucose Thresholds & Sources
This document details the specific blood glucose ranges reported by four authoritative clinical sources, alongside the thresholds used by SugarCalc (April 2026). It also provides the rationale for maintaining a 4.0 mmol/L lower bound for Type 2 diabetes.
Thresholds by Source
| Diabetes Type | Condition | SugarCalc | ADA 2024 | NICE NG17 | NICE NG28 | 2024 ICR |
|---|---|---|---|---|---|---|
| Type 1 | Fasting / Waking | 4.0 to 7.0 | 4.4 to 7.2 | 5.0 to 7.0 | ~ | ~ |
| Type 1 | Post-meal (1-2 hrs) | 5.0 to 9.0 | < 10.0 | 5.0 to 9.0 | ~ | ~ |
| Type 2 | Fasting / Waking | 4.0 to 7.2 | 4.4 to 7.2 | ~ | ~ * | ~ |
| Type 2 | Post-meal (1-2 hrs) | 5.0 to 10.0 | < 10.0 | ~ | ~ * | ~ |
| All Types | DKA Risk (Critical High) | 11.1 | ~ | ~ | ~ | ≥ 11.1 |
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All thresholds stated in mmol/L.
Note: NICE NG28 (Type 2 Diabetes) primarily focuses on HbA1c targets (typically 48 mmol/mol or 6.5%) rather than specific daily capillary blood glucose ranges, which is why the ADA 2024 guidelines are used as the primary reference for Type 2 daily targets.
Rationale: The Bounds for Type 1 Fasting / Waking
The ADA 2024 Standards of Care recommend a fasting range of 4.4 to 7.2 mmol/L for Type 1 diabetes, while NICE NG17 recommends 5.0 to 7.0 mmol/L. However, SugarCalc has adopted a broader range of 4.0 to 7.0 mmol/L.
1. The Lower Bound & the Universal Definition of Hypoglycaemia
As with Type 2 diabetes, the ADA defines Level 1 hypoglycaemia as < 3.9 mmol/L (70 mg/dL), and the NHS and Diabetes UK use < 4.0 mmol/L (72 mg/dL). For safety, SugarCalc adopts the higher figure, 4.0 mmol/L (72 mg/dL), as its warning threshold. Setting the lower bound at 4.4 mmol/L or 5.0 mmol/L would trigger "Low Blood Sugar" warnings for safe, normal readings (e.g., 4.2 mmol/L or 4.8 mmol/L). This could lead to unnecessary treatment and rebound hyperglycaemia.
2. The Lower Bound & "Target Goal" vs. "Warning Threshold"
The ADA (4.4 mmol/L) and NICE (5.0 mmol/L) figures are clinical target goals designed to provide a safe buffer above the danger zone, especially for patients on insulin. SugarCalc's 4.0 mmol/L is a warning threshold. The app should only alert a user when medical action (consuming fast-acting carbohydrates) is required.
3. The Upper Bound: 7.0 vs 7.2 mmol/L
For the upper bound, the ADA recommends 7.2 mmol/L, while NICE NG17 recommends a slightly tighter 7.0 mmol/L. SugarCalc has adopted the 7.0 mmol/L threshold.
This decision prioritises tighter glycaemic control for Type 1 patients. Because Type 1 diabetes involves an absolute lack of insulin, post-meal spikes can occur rapidly if the fasting baseline is already elevated. By warning the user at 7.1 mmol/L rather than waiting for 7.3 mmol/L, SugarCalc encourages earlier, minor corrective actions (or simply heightened awareness before a meal), which helps prevent larger hyperglycaemic excursions later in the day.
4. Balancing Control and Safety
By using 4.0 to 7.0 mmol/L, SugarCalc aligns with the NICE upper limit for good control (7.0) while maintaining the universally accepted safety floor for hypoglycaemia (4.0). This ensures users are not bombarded with false alarms for safe low-end readings, while still being proactively alerted to rising high-end readings.
Rationale: The Bounds for Type 2 Diabetes
Although the ADA 2024 Standards of Care recommend a fasting range of 4.4 to 7.2 mmol/L for Type 2 diabetes, SugarCalc has adopted 4.0 to 7.2 mmol/L.
1. The Lower Bound & the Universal Definition of Hypoglycaemia
Major diabetes organisations define hypoglycaemia (low blood sugar) at almost the same point. The American Diabetes Association (ADA) defines Level 1 hypoglycaemia as < 3.9 mmol/L (70 mg/dL). In the UK, the NHS and Diabetes UK treat any reading below 4.0 mmol/L (72 mg/dL) as a hypo ("4 is the floor"). For safety, SugarCalc adopts the higher of the two, 4.0 mmol/L (72 mg/dL), as its warning threshold, so a low reading is never flagged later than either definition would flag it (see "Target Goal" vs. "Warning Threshold" below).
If SugarCalc were to set the lower bound at 4.4 mmol/L, the application would issue a "Low Blood Sugar" warning for a reading of 4.2 mmol/L. Clinically, a reading of 4.2 mmol/L is entirely normal and safe; it does not require the patient to consume fast-acting carbohydrates. Warning a patient at 4.2 mmol/L could lead to unnecessary treatment (over-treating a non-low), which could cause rebound hyperglycaemia and weight gain.
2. The Lower Bound & "Target Goal" vs. "Warning Threshold"
There is a subtle but important difference between a clinical target goal and an application warning threshold:
- The ADA Target (4.4 mmol/L): This is the goal doctors set for patients to aim for. It provides a safe buffer above the actual danger zone.
- The SugarCalc Threshold (4.0 mmol/L): This is the trigger point for an alert. The app should only alert a user when an action is required. Because no medical action is required for a reading between 4.0 and 4.3 mmol/L, triggering a warning in this narrow band could cause "alarm fatigue" and anxiety.
3. Consistency Across Diabetes Types
Maintaining 4.0 mmol/L as the absolute floor across Type 1 and Type 2 diabetes ensures consistency in the app's logic. The physiological danger zone for the human brain begins below 4.0 mmol/L, regardless of the type of diabetes.
By using 4.0 to 7.2 mmol/L, SugarCalc balances the ADA's upper limit for good control (7.2) with the universally accepted safety floor for hypoglycaemia (4.0), ensuring users only receive warnings when medical action is actually necessary.
References
[ADA 2024] American Diabetes Association Professional Practice Committee. (2024). 6. Glycemic Goals and Hypoglycemia: Standards of Care in Diabetes—2024. Diabetes Care, 47(Supplement_1), S111–S125. https://doi.org/10.2337/dc24-S006
Online Access: American Diabetes Association. (2024). 6. Glycemic Goals and Hypoglycemia: Standards of Care in Diabetes 2024. Retrieved April 14, 2026, from https://diabetesjournals.org/care/article/47/Supplement_1/S111/153951/6-Glycemic-Goals-and-Hypoglycemia-Standards-of-Care-in
[NG17] National Institute for Health and Care Excellence. (2022, August 17). Type 1 diabetes in adults: diagnosis and management (NG17). Section 1.6: Blood glucose management.
Online Access: National Institute for Health and Care Excellence. (2022, August 17). Type 1 diabetes in adults: diagnosis and management. Retrieved April 14, 2026, from https://www.nice.org.uk/guidance/ng17/chapter/1-Recommendations#blood-glucose-management
[NG28] National Institute for Health and Care Excellence. (2026, February 18). Type 2 diabetes in adults: management (NG28). Section 1.5: HbA1c measurement and targets.
Online Access: National Institute for Health and Care Excellence. (2026, February 18). Type 2 diabetes in adults: management. Retrieved April 14, 2026, from https://www.nice.org.uk/guidance/ng28/chapter/Blood-glucose-management
[2024 ICR] Umpierrez, G. E., et al. (2024). Hyperglycemic Crises in Adults With Diabetes: A Consensus Report. Diabetes Care, 47(8), 1257–1273. https://doi.org/10.2337/dci24-0013
Online Access: American Diabetes Association. (2024). Hyperglycemic Crises in Adults With Diabetes: A Consensus Report. Retrieved April 14, 2026, from https://diabetesjournals.org/care/article/47/8/1257/156808/Hyperglycemic-Crises-in-Adults-With-Diabetes-A