The technology

d‑Nav (Hygieia) is a phone app that aims to guide insulin dosing in adults with type 2 diabetes. It is primarily indicated for those needing insulin in which blood glucose or haemoglobin A1c (HbA1c) targets are not being reached. The technology comprises of 2 elements, a phone app for the person with type 2 diabetes and the d‑Nav website for use by healthcare professionals.

The phone app is used by the patient to a enter glucose reading and get a recommended insulin dose. The blood glucose reading is taken from any blood glucose meter or a continuous glucose monitor. It is entered into the app either manually through the phone keypad or through the cloud from a linked blood glucose meter. Based on glucose readings and the user's current insulin instructions and history of events, the d‑Nav Get‑Dose Library algorithm calculates a new recommended insulin dose and updates current insulin instructions if needed.

The app is set up by a healthcare professional using the d‑Nav website. Setup consists of entering the prescribed starting insulin dose instructions and sending the information to the patient's app. Insulin instructions include the treatment plan, insulin drug type, and dose(s).

The d‑Nav app is available for both iOS and Android devices.

The d‑Nav app is a replacement of the d‑Nav device. The device was comprised of a handheld device with a built‑in glucose meter. The app uses the same software and Get‑Dose Library algorithm as the device but allows additional connectivity with the healthcare professional website and a linked blood glucose meter through the cloud.


The device is designed to help optimise insulin dosing to reduce high HbA1c levels into the target range while reducing the rate of hypoglycaemic events. The company states that the d‑Nav app includes safety checks to stop insulin dose changes if the total daily dose exceeds the healthcare professional's set threshold.

Current care pathway

NICE's guideline on type 2 diabetes in adults: management states that insulin-based treatment for people with type 2 diabetes is considered as an option for the second intensification of drug treatment when current treatments have not been able to control HbA1c levels. The type of insulin and dose prescribed depends on factors including the ability to administer treatment, HbA1c levels, the likelihood of becoming hypoglycaemic, and the use of other glucose‑lowering drugs.

When starting insulin therapy in adults with type 2 diabetes, a structured programme is recommended which includes:

  • continuing telephone support

  • self-monitoring

  • dose titration to target levels

  • dietary understanding

  • management of hypoglycaemia

  • management of acute changes in plasma glucose control

  • support from an appropriately trained and experienced healthcare professional.

The following publications have been identified as relevant to this care pathway:

Population, setting and intended user

d‑Nav is intended to be used to help optimise insulin dosage for people with type 2 diabetes. The person's insulin treatment plan would be entered by an appropriately trained healthcare professional through the d‑Nav website. The patient would use the device at home alongside a glucose meter or continuous glucose monitor. People would need a smartphone and regular internet access to use the device and get the Get‑Dose Library updates from the cloud.

The company provides training for healthcare professionals and patients when they start using d‑Nav. The company also provides ongoing technical support with a freephone service.


Technology costs

The cost of the d‑Nav app has not yet been decided for the NHS in England. The company has advised that the list price of the technology will be about £100 per person per month (excluding VAT).

Costs of standard care

Standard care would be the cost of appointments with a healthcare professional to change insulin dosage. If seen by a specialist nurse the cost would be between £79 (if the appointment was face to face) and £39 (if the appointment was not face to face; N15AF and N15AN; National schedule of NHS costs for 2019 to 2020). A non‑admitted face‑to‑face follow‑up appointment would cost £154.32 (WF01A; National schedule of NHS costs for 2019 to 2020). Follow‑up care in primary care or in the community may be less costly. The d‑Nav technology would be used in addition to routine follow ups with healthcare professionals.

Resource consequences

The physical version of the device has been in use in the NHS in Northern Ireland since 2013. There, GPs can refer people directly to the d‑Nav service or refer them to the hospital diabetes services to consider suitability for using d‑Nav.

The app alone version of the device has been used in the US for over 3 years. The technology is recommended in the US by the American Diabetes Association's standards of medical care in diabetes (2021) as an alternative to continuous glucose monitoring, to help people with insulin dosing improve HbA1c with minimal hypoglycaemia.

d‑Nav would be used in addition to standard care. Adopting d‑Nav could improve management of type 2 diabetes and reduce the time needed by clinicians to optimise insulin dosage. This could help maintain optimal HbA1c levels and reduce the number of hypoglycaemic events. This could reduce the likelihood of developing diabetes‑related complications, reduce hospitalisation and reduce additional NHS resource use. Better control of HbA1c levels could also reduce the need for additional blood glucose control medications.

A cost-effectiveness analysis of the d‑Nav device in people with diabetes in the NHS who are at high risk of foot ulcers (defined as those who have an HbA1c of 9% or greater) has been reported by Green and Taylor (2016). It found that d‑Nav was cost-saving by £1,278 and produced more quality-adjusted life years (0.009) than standard care. One further US cost analysis (Schneider et al. 2018) was published looking at the impact of d‑Nav on non‑insulin pharmaceutical expenses. It found that device use led to a reduction in cost associated with the need for additional diabetes medications. Both studies were based on the physical device rather than the app.