The application relates to a system for measuring blood glucose variability, by acquiring a plurality of blood glucose data points over a predetermined time period. The Board noted that the technical effect was achieved only for longer periods of observation. Since the claim did not specify the period, the technical effect was not achieved over the whole scope of the claim. However, the amended claim with the limitation of the specific period (7 days) rendered the distinguishing features technical and thus was considered for the assessment of the inventive step, and found to be inventive. Here are the practical takeaways from the decision T 2681/16 of March 14, 2022 of the Technical Board of Appeal 3.2.02:

Key takeaways

Features that relate solely to the algorithm used in the claimed system, when taken in isolation, are non-technical. As such, they can support the presence of an inventive step only if they credibly contribute to producing a technical effect serving a technical purpose

It is irrelevant if features might contribute to the technical character of the claimed subject-matter and thus to an inventive step for other parts of the claimed subject-matter. A prerequisite for meeting the requirement that the claimed invention is inventive over the whole scope of the claim is indeed that it is also technical over the whole scope.  

The invention

Blood glucose variability is an important parameter in diabetes management, and monitoring this parameter may help patients to improve their behaviour and self-treatment practices to reduce the risk.

For this purpose, the patent application provides a system for measuring blood glucose variability, by acquiring a plurality of blood glucose data points over a predetermined time period, for example over a number M of days; a processor programmed to calculate a risk index based on the acquired blood glucose data points and to classify it into a risk category, and a display module to display the determined risk category. For this, an algorithm to calculate the risk index from the acquired blood glucose data points is presented.

The applicant also provided experimental validation studies in the description confirming, that when calculated from a sufficiently large set of blood glucose data points spanning a sufficiently long period of time, the risk index turns out to be equally predictive. Therefore, the method was a reliable measure of the overall blood glucose variability compared to other measures of variability previously used.

  • Claim 1 (Main Request)

  • Claim 1 (Second Auxiliary Request)

Is it patentable?

The Examining Division refused the application and considered the subject-matter of the claims lacked inventive steps starting from D5 (B. P. Kovatchev et al., “Quantifying Temporal Glucose Variability in Diabetes via Continuous Glucose Monitoring: Mathematical Methods and Clinical Application”, Diabetes Technology & Therapeutics, vol. 7, no. 6, 2005).

In the Appeal proceedings, the Board raised new objections to the lack of clarity and support in the description (Art.84 EPC). The Board indicated that although the claims included a predetermined time as a day, the description consistently discloses that the risk index must be calculated over a period of time. The applicant filed amended claims (Second to fourth Auxiliary Request) including features which overcame this objection.

The Board then considered if the Second Auxiliary Request was inventive over the cited document D5, which discloses a statistical risk analysis to quantify the blood glucose variability of a diabetic patient from self-monitored blood glucose data points.

The appellant argued that the claim was inventive in that the way the acquired blood glucose data points were processed to derive a measure of the blood glucose variability (features (a) – (c) ) and how the average daily risk range was calculated.

The Board did not agree with the argument:

3.2.3 As acknowledged by the appellant, features (a)-(c) relate solely to the algorithm used in the claimed system to process the acquired blood glucose data points. These features, when taken in isolation, are non-technical. As such, they can support the presence of an inventive step only if they credibly contribute to producing a technical effect serving a technical purpose (Case Law of the Boards of Appeal, 9th edition, 2019, I.D.9.1.3 c)).

3.2.4 The appellant submitted that these features had the technical effect of providing an overall measure of the glucose variability (i.e. equally sensitive to both hypo- and hyperglycemic events) and a prediction of glycemic events that were better than, or at least alternative to, those used in D5.

3.2.5 While this effect does appear to be achieved for longer periods of observation, as in the experimental validation studies reported in the description, the Board does not find it credible that it is achieved if a very small number of blood glucose data points is used to calculate ADRR, in particular when the minimum number of blood glucose data points required by claim 1 is used, i.e. two data points spanning a period of one day only; see the discussion in point 2.1 above, especially the last paragraph. The appellant did not provide any convincing arguments demonstrating that this was the case.

3.2.6 It follows that, at least for these parts of the claimed subject-matter, features (a)-(c) do not contribute to the technical character of the claimed subject-matter and therefore cannot support the presence of an inventive step.

Contrary to the appellant’s contention, it is irrelevant that features (a)-(c) might contribute to the technical character of the claimed subject-matter and thus to an inventive step for other parts of the claimed subject-matter, in particular when more blood glucose data points are used. A prerequisite for meeting the requirement that the claimed invention is inventive over the whole scope of the claim is indeed that it is also technical over the whole scope. The requirement has not been met, as features (a)-(c) contribute to the technical character only for certain specific embodiments of the claimed invention (see G 1/19, Reasons 84).

The fact that claim 1 defines a system and not a method, as put forward by the appellant, is immaterial. Indeed, claim 1 does not merely require that the system be suitable for calculating ADRR from a higher number of blood glucose data points. Rather, the minimum number of blood glucose data points used to calculate ADRR is a feature of the algorithm specifically programmed in the processor of the claimed system. It is also a feature of the acquisition module, which must be specifically adapted to acquire at least this number of blood glucose data points. Thus, this minimum number is a feature of the claimed system itself.

Since the claim was not technical over the whole scope (i.e., the claimed technical effect of the overall measure of the glucose variability and a more reliable risk prediction was not credible for a shorter period of observation), the Board considered the claim lacked inventive step.

The applicant then amended the claim and filed a fourth Auxiliary Request by changing the expression “at least one day” to “at least seven days” and using at least three blood glucose data point readings per day.

  • Claim 1 (Fourth Auxiliary Request)

The Board noted that these features were not obvious for the following reasons:

6.2.1 Claim 1 of the fourth auxiliary request requires a minimum of 3 x 7 = 21 data points spanning a period of seven days. Even though this corresponds to a smaller set of data points than used in the experimental validations studies reported in the description (see point 2.1 above), the Board finds it credible that this number of blood glucose data points and the period they span still represent a sufficiently large sample to be statistically significant. The Board is therefore satisfied that, in these conditions, the technical effect put forward by the appellant (point 3.2.4 above) is achieved over the whole claimed subject-matter. Accordingly, features (a)-(c) can a priori support the presence of an inventive step.

6.2.2 The Board concurs with the appellant’s view that, contrary to the Examining Division’s view (point 15.4.1 of the decision under appeal), the person skilled in the art, starting from D5, would have had no motivation to modify the definition of LBGI and HBGI given in D5 so as to determine maximum risk values instead of average risk values (feature (a)).

Indeed, as disclosed in D5, page 852, top of the left-hand column, the risk indices LBGI and HBGI have been specifically constructed so as to be a “measure of the frequency and extent” of the low and high blood glucose readings, respectively. Replacing the average risk value averaged over each period of time by the maximum value reached over said period would erase information on the frequency and extent of the blood glucose excursions occurring during that period of time, as argued by the appellant. This would be contrary to the purpose of the risk analysis presented in D5. Without the benefit of hindsight, the person skilled in the art would have therefore not envisaged such a modification.

Moreover, none of the other documents D1-D4 and D6 cited in the decision under appeal discloses or suggests feature (a).

At least for this reason, the subject-matter of claim 1 of the fourth auxiliary request involves an inventive step over D5, contrary to the Examining Division’s finding.

Therefore, the Board concluded that the subject-matter of the claim of fourth Auxiliary Request involves an inventive step, and the appeal is allowed with an order to grant a patent

More information

You can read the whole decision here: T 2681/16 of March 14, 2022 of the Technical Board of Appeal 3.2.02

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