Useful Study of Continuous Glucose Monitoring (CGM) with Simultaneous Smartphone Evaluation

Bando H, Bando M and Urasaki H

Published on: 2025-09-27

Abstract

Continuous Glucose Monitoring (CGM) can show detail blood glucose variability. FreeStyle Libre 3 with smartphone has been introduced to clinical practice. Current case is nurse aged 60 years who has stable situation as HbA1c 6.5-6.8%. The aim would be the study of relationship among Post-prandial hyperglycemia (PPH), carbohydrate intake, pre-prandial milk, clinical effect of α-glucosidase inhibitor (α-GI). Her pre-prandial and post-prandial blood glucose were around 100mg/dL, and 200-250mg/dL, respectively. When consuming carbohydrate, PPH seemed to be higher and broader with longer hours. Time in range (TIR) will become time in tight range (TITR) for ideal control in the future.

Keywords

post-prandial hyperglycemia (PPH); Continuous glucose monitoring (CGM); Pre-prandial milk; Freestyle libre 3; Smartphone

Introduction

For the glucose variability in diabetic patients, the measurement of continuous glucose monitoring (CGM) has been applied by Free Style Libre [1]. Several types of CGM have been used for detail evaluation for patients with type 2 or type 1 diabetic cases (T2D, T1D) [2]. Various studies for CGM apparatus revealed the satisfactory quality of detail changing in simultaneous blood glucose [3]. As recent clinical development of CGM, more ideal glucose situation has been in discussion [4]. They include several clinical markers, such as time in range (TIR), times below range (TBR), time above range (TAR), and mean difference (MD) [5]. Furthermore, medical technology has been more advanced, where simultaneous application of smartphone has been introduced to actual medical practice [6].

Authors et al. continued for long diabetic research and practice for various types of patients, associated with Metabolic syndrome (Met-S) and atherosclerotic cardiovascular disease (ASCVD) [7,8]. During our research, CGM has been applied to some cases for evaluating detail glucose variability [9]. Our team has some opportunities to use CGM system associated with simultaneous smartphone application. As a matter of fact, the combination of CGM plus smartphone seems to be convenient and useful [10]. We happened to have a meaningful diabetic case, who is a nurse and applied CGM + smartphone for detail evaluation of daily blood glucose variability in response to a variety of meals. The results associated with some perspectives will be described in current article.

Case Presentation

Case and Method

The patient was a 60-year-old female nurse.?She was diagnosed as type 2 diabetes (T2D) about 10 years ago. , and has continued standard low carbohydrate diet (LCD) for years. She did not have particular diabetic complications, and her HbA1c persisted about 6.5-6.8%. Body mass index (BMI) persisted 23-24 kg/m². In current research protocol, she used FreeStyle Libre 3 associated with her smartphone for 14 days in August 2025. She can tolerate the evaluation of detail glucose variability well during the period.

Results

CGM measurement was successful from August 18 to Sep 1, 2025. The result of the average blood glucose for 2 weeks is shown in Figure 1. The mealtime was 0700h, 1200h, and 1800h with stable daily rhythm. Blood glucose level within the recommended range (80-170 mg/dL) are considered to be in good condition.

In the current CGM system, satisfactory area has been indicated by green-colored line or space. As TIR, the common period was formerly 70-180mg/dL, but TIR is set to be 80-170mg/dL in the latest FreeStyle Libre 3+ smartphone.Figure 1: Average Blood Glucose Variability.

Detail relationship between taking meals and simultaneous blood glucose is summarized in Figure 2, 3, 4 and 5. For August 18-19, three peaks of blood glucose were found, in which post-prandial hyperglycemia (PPH) is distinct in each meal a day (Figure 2). The degree of the peaks are from 206mg/dL to 259mg/dL. The periods of PPH seem to be about 3-4 hours. On Aug 22, three peaks of glucose are found as higher than 250mg/dL (Figure 3 left). Blood glucose before meal was around 100mg/dL, and PPH were more than 150 mg/dL, respectively. The ingested carbohydrate was 60g, 96g, and 81g, respectively. The time period of PPH in these 3 situations were different, due to the carbo amount. During August 23 night, she took rice 80g and potato10g, and prolonged PPH was found about 5-6 hours, which were rather longer than usual (Figure 3 right).

Figure 2: Blood Glucose and Taking Meal for August 18-19.

Figure 3: Blood Glucose and taking Meal for August 22-23.

For August 24-25, two additional nutritional trials were conducted (Figure 4). One is taking pre-prandial milk 70ml just before the meal (green color), and another is taking miglitol 50mg just before the meal (pink color). When taking pre-prandial milk twice in August 24, PPH seemed to be decreased in breakfast and supper (Figure 4 left). On the other hand, PPH was usually observed up to more than 250 mg/dL after lunch without pre-prandial milk. On August 25, remarkable findings were found (Figure 4 right). Post-prandial glucose peak after breakfast was less than 170mg/dL, suggesting decreased PPH by pre-prandial milk taking. Post-prandial glucose after supper was kept less than 170mg/dL for long, suggesting clinical efficacy of miglitol given before supper. During August 26-27, clinical trials included pre-prandial milk once and pre-prandial miglitol 3 times (Figure 5). As impressive response, miglitol administration brought slower elevation of PPH in the supper on August 26, and in the lunch on August 27. Miglitol is one of the alfa-glucosidase inhibitors (α-GIs), and it is likely to provide diabetic patient decreasing the level of PPH.

Figure 4: Blood Glucose and taking Meal for August 24-25.

Taking Milk 70mL just before Meal (Green ?)

Taking Miglitol Med just before Meal (Pink ?)

Figure 5: Blood Glucose and taking Meal for August 26-27.

Taking Milk 70mL just before Meal (Green ?)

Taking Miglitol Med just before Meal (Pink ?)

In Japan, typical Japanese lunch box can be bought anywhere and anytime in the convenience shop. The common type of lunch box is shown (Figure 6). It contains rice (carb 60g), potato (8g), pumpkin (8g), grilled fish (6g), and cutlet (4g), totally 86g in carbohydrate. Japanese cuisine is characteristic for including carbohydrate in usual meal.

Figure 6: Typical Japanese Lunch Box.

Discussion

The US Food and Drug Administration (FDA) has recognized FreeStyle Libre 3 real-time CGM, and clinical application has been developed with the support of American Diabetes Association (ADA) [11,12]. In addition, recent studies have proposed the precision of several data from CGM [13,14]. For current study, precise real-time fluctuation of blood glucose has been captured. Beneficial aspects will give meaningful and impressive perspectives for diabetic care associated with satisfactory treatment.

Several points can be considered from the data obtained in this study. An interesting result was observed on August 22. She ingested 60g, 96g, and 81g of carbohydrates for 3 meals, and the PPH was approximately the same as 150mg/dL. A general trend has been known regarding the relationship of carbohydrate intake and blood glucose rise. As a rule, 1g of carbohydrate can increase blood glucose levels by 1mg/dL, 3mg/dL, and 5mg/dL in healthy individuals, T2D, and T1D patient, respectively [15]. The fact that the PPH was nearly the same in all three cases suggests that other factors may be involved. These factors may include i) rapid absorption, ii) vitamins and caffeine, iii) the influence of liquids such as carbonated drink and sports drink, iv) the amount of protein and amino acids consumed, and v) the influence of hunger prior to breakfast, lunch, and dinner.

Concerning the ideal range of blood glucose, time in range (TIR) has been usually known as 70-180mg/dL. In this report, recommended TIR in the smartphone by the FreeStyle Libre 3 are set to be as 80-170mg/dL. It is a little narrower than the previous standard. Recently, a novel concept is proposed that is time in tight range (TITR) [16]. TITR would be more ideal range as 70-140 mg/dL, which is narrower than TIR. As CGM study including TITR, TIR and blood glucose, lots of patients were categorized into 4 groups. In comparison with highest TITR and TIR group, the lowest glycemic situation was observed as 23-30% of glucose coefficient of variation (CV). It is indeed that TITR is too narrower range, but it will become the ideal range to maintain for future anti-aging medicine.

The authors and co-researchers have worked concerning FreeStyle Libre 3 for long. We had a remarkable and meaningful experience for CGM project. We will take most advantage of CGM into nutritional education and diabetic practice for patient care in the future. Some limitations may be present concerning this report. CGM has been evaluated as useful and practical measurement so far [8,17]. However, it is not enough for just obtaining the glucose data, but intensive, simultaneous, and meaningful evaluation associated with behavior response will be required for the diabetic patient [18].

In summary, CGM can contribute much with adequate testing and reflecting. As historical progress of CGM, future development is expected for precise data, convenience, and advice leading to well-being from individual and social points of view.

Conflict of Interest

The authors have read and approved the final version of the manuscript.

The authors have no conflicts of interest to declare.

Funding

There was no funding received for this paper.

International Journal of Endocrinology and Diabetes