The American Diabetes Association (ADA) recently released the "Standards of Care in Diabetes-2025 (SoC-25)"[1]. The ADA has continued to recommend low-carbohydrate diets (LCD) for diabetes care for 6 years. LCD has been more understood broadly in medical and health care region for two decades. Authors have continued medical, social and ecological development for LCD prevalence through various activities of Japan LCD Promotion Association (JLCDPA) and continued [2]. We have seen great success using LCDs in diabetes patients. Long-term data are limited, but we recorded great glycemic control for almost 2 decades. LCDs are effective at maintaining adequate glycemic control and reducing polypharmacy, adverse outcomes, and medical care costs. In this article, some perspectives are presented concerning SoC-25 and movement of LCD so far.

ADA has shown the comments about the relationships of nutrients and blood glucose, where 50% of protein and <10% of lipid would change into post-prandial hyperglycemia in 1997. However, this comments were deleted in 2004 [3]. According to the obtained medical evidence, ADA has changed the scientific reports concerning the relationships of nutrients and blood glucose. The consensus recommendation has been announced from ADA until now [4].

In Japan, the first edition of the Food Exchange List (FDL), which is like a bible for the Japan Diabetes Society (JDS), was published in 1965 [5]. At that time, emphasis was placed on appropriate calories. The explanation stated in the FDL principles of dietary therapy is as follows:

1) Appropriate calories

2) Limitation of carbohydrates

3) Balance of carbohydrates, proteins and lipids

4) appropriate supplementation of vitamins and minerals

 The second principle of the FDL recommends carbohydrate restriction unambiguously with the statement, "Limitation of carbohydrates". In the second edition in 1969, the phrase "Limitation of carbohydrates" was removed, and the principles were revised to:

1) Appropriate calories (calorie restriction)

2) Balance of carbohydrates, proteins, and lipids

3) Appropriate supplementation of vitamins and minerals

In the second edition of FDL, "carbohydrate restriction" was removed from the principles of diabetic dietary therapy and "calorie restriction" was introduced. From this point on, FDLs were all about "energy-restricted diets" until the 7th edition, which was revised for the first time in 11 years in 2013 [6]. For decade, the recognition for carbo and blood glucose in Japan has been changed from the actual medical practice. Consequently, there was a positive change in the content of dietary therapy in the Diabetes Treatment Guidelines 2024, which moved closer to low carbohydrate diets (LCD) [7]). The main principles are described in the followings:

1) Energy-restricted diets are recommended for blood glucose control in overweight/obese T2D patients.

2) LCDs are useful for blood glucose control in T2D patients (but only for 6-12 months).

3) Carbohydrate counting is useful for blood glucose control in type 1 diabetes (T1D) patients.

4) Low glycemic index (LGI) diets are useful for blood glucose control in T2D patients.

5) Active dietary fiber intake is useful for blood glucose control in T2D.

The authors have continued treating various diabetic patients so far. Limiting total carbohydrate amount and focusing on the quality of carbohydrates has been effective in achieving good glucose control [2]. We have separated LCD into three tiers based on a percentage of total dietary carbohydrate intake. Super-LCD, standard-LCD, and petit-LCD are defined as 12%, 26%, and 40% of daily caloric intake from carbohydrates, respectively [8]. From our experiences, two impressive cases will be presented.

Case 1 was in her 50s, who was diagnosed as T2D with HbA1c 7.2%, 155.2 cm, 47.0 kg, and BMI 19.5 kg/m². She was hospitalized at Takao Hospital in January 2022 and wore continuous glucose monitoring (CGM) for 14 days with no oral hypoglycemic agents (OHAs) [2]. She showed HbA1c 6.2%, FPG 104 mg/dl on admission. She was provided the usual diabetic formula for 2 days, represented by the brown line for day 1 and the blue line for day 2 (Figure 1). Its formula was along with the “standard diabetic diet” recommended by JDS [9], with 1800 kcal/day intake. On day 2, she had postprandial hyperglycemia exceeding 180 mg/dl three times a day, at breakfast, lunch, and dinner. From the 3rd day onwards, she was on a "super LCD" of 1800 kcal/day, and her postprandial hyperglycemia improved significantly and did not exceed 150 mg/dl. She had plaque burden in both carotid arteries.

Figure 1: Normalized glucose variability on starting day by super-LCD.

Case 2 is a 51-year-old male patient with T2D for following up 18 years (Figure 2). His first visit was in March 7, 2007, with HbA1c 11.4%, fasting plasma glucose (FPG) 389 mg/dL, 66kg and BMI 24.2kg/m². The patient immediately started super-LCD, and HbA1c was decreased to 9.0% and FPG 143mg/dL on April 6, 2007. Currently, he keeps HbA1c 5.7% and 55 kg in weight with ideal glucose control in December 2024.

Figure 2: Super-LCD would be effective enough without OHA for long years.

According to the American Diabetes Association (ADA), only carbohydrates directly affect blood sugar levels, and proteins and lipids have no effect [10]. This is the principle of the three main nutritional elements for blood glucose (BG). Protein indirectly raises BG via glucagon, but since insulin is secreted at the same time, it has no effect on BG in healthy people. For T1D, endogenous insulin cannot be secreted, and then protein indirectly raises slightly BG. Fat does not affect BG levels.

As mentioned above, LCD focuses on the restriction of carbohydrate intake as much as possible to prevent postprandial hyperglycemia. Even a super LCD without a staple food for three meals contains about 10g of carbohydrates from vegetables, so it is not completely carbohydrate-free. LCD improves postprandial hyperglycemia but does not cause hypoglycemia because gluconeogenesis occurs in the liver. The ADA officially approved an LCD in its guidelines in October, 2013. The consensus recommendation in April 2019 showed that LCDs “are among the most studied eating patterns for T2D” [11]. Since then, the 2020, 2021, 2022, 2023, and 2024 guidelines have expressed the same viewpoint.

The JDS decided to stop recommending carbohydrate restriction in 1969. However, recent recommendations from the JDS allow for carbohydrate restriction (Figure 3a). On the other hand, authors have disseminated useful information regarding LCDs to patients, providers, affiliates, and researchers through the JLCDPA [12] (Figure 3b).

Figure 3: Educating textbooks for diabetic patients.

a: Food Exchange List (FDL) 7^th Ed by JDS.

b: Practical LCD method by Dr. Ebe and JLCDPA.

In summary, we have found great successful results incorporating strategic implementation of LCDs in diabetes patients [13]. Long-term data are limited, but we recorded various glycemic control for almost two decades. Nowadays, diabetes is increasing worldwide and healthcare costs are becoming unmanageable across the globe, we must find ways to be more cost-effective. The burden of polypharmacy and insulin administration on patients has also been lessened.

Conflict of interest: The authors declare no conflict of interest.

Funding: There was no funding received for this paper.

1. American Diabetes Association Professional Practice Committee. 5. Facilitating Positive Health Behaviors and Well-being to Improve Health Outcomes: Standards of Care in Diabetes-2025. Diabetes Care. 2025; 48: S86-S127.
2. Ebe K, Hashimoto M, Bando H, Bando M, Muneta T. Proposal of Meal Tolerance Test (MTT) For Investigating Ability of Insulin Secretion for Small Carbohydrate Load. Diab Res Open Access. 2020; 2: 31-37.
3. American Diabetes Association. Standards of medical care in diabetes--2009. Diabetes Care. 2009; 32: S13-61.
4. 8. Obesity and Weight Management for the Prevention and Treatment of Type 2 Diabetes: Standards of Care in Diabetes–2025. Diabetes Care. 2025; 48: S167–S180.
5. Japan Diabetes Society.
6. Fukui M, Yamamoto K, Ishida K. Developing diet therapy for diabetes. The point of 7^th J Jap Diabetes Soc 2013; 56: 922-925.
7. Japan Diabetes Society (JDS). Chapter 3. Diet therapy. The guideline of diabetes practice.
8. Bando H, Ebe K. Beneficial and Convenient Method of Low Carbohydrate Diet (LCD) as Petite, Standard and Super LCD. Asp Biomed Clin Case Rep. 2023; 7: 1-4.
9. Araki E, Goto A, Kondo T, Noda M, Noto H, Origasa H, et al. Japanese Clinical Practice Guideline for Diabetes 2019. Diabetol Int. 2020; 11: 165-223.
10. Franz MJ, Bantle JP, Beebe CA, Brunzell JD, Chiasson JL, Garg A, et al. American Diabetes Association. Nutrition principles and recommendations in diabetes. Diabetes Care. 2004; 27: S36-46.
11. Evert AB, Dennison M, Gardner CD, Garvey WT, Lau KHK, MacLeod J, et al. Nutrition Therapy for Adults With Diabetes or Prediabetes: A Consensus Report. Diabetes Care. 2019; 42: 731-754.
12. Ebe K, Bando H. “New era of diet therapy and research including Low Carbohydrate Diet (LCD)”, Asp Biomed Clin Case Rep. 2018; 2: 1-3.
13. Ebe K, Wood M and Bando H. Preventing Post-Prandial Elevation of Blood Glucose by Breakfast with Less Carbohydrate. Int J Case Rep Clin Image. 2024; 6: 219.