Letter to the Editor - Response to Study on 90 g/day Low-Carbohydrate Diet for Type 2 Diabetes

Sep 28, 2026

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Letter to the editor responding to Wang et al.’s study on an 18-month 90 g/day low-carbohydrate diet in older adults with type 2 diabetes. The author commends retention and long-term data while highlighting that glycemic improvements may be confounded by medication deescalation and increased physical activity in the intervention group. The letter suggests analyses adjusting for medication intensity and activity changes or sensitivity analyses excluding therapy modifications to clarify causal effects on HbA1c, glucose, and frailty.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages1

Reading Time3 min

AccessFree to download

Letter to the Editor

Main comments on study findings

Consideration of medication effect

Consideration of physical activity changes

Suggestions for future analyses

Disclosure and data availability

LETTER TO THE EDITOR Letter to the editor in response to ‘A 90 g/day low-carbohydrate diet improved glycemic control without decreasing frailty in older patients with type 2 diabetes’ by Wang et al. To the Editor, I read with great interest the article by Wang et al., which assessed the effects of an 18-month, 90 g/day low-carbohydrate diet (LCD) in older adults with type 2 diabetes1. Running a nutritional trial of such length in an elderly cohort is demanding, and the investigators deserve recognition for achieving excellent retention and generating valuable long-term data. The reported improvements in HbA1c (-0.5% vs –0.2% in controls), 2-h post-meal glucose, and waist circumference, all without worsening frailty, are noteworthy. These ﬁndings are especially relevant given the growing burden of diabetes in older adults, where nutrition strategies that support metabolic health while maintaining physical function are urgently required. However, two considerations need tobe taken into account before the beneﬁts can be ascribed solely to carbohydrate restriction. First, the Medication Effect Score dropped substantially in the LCD group at 18 months (-0.45 – 0.71). A reduction in antihyperglycemic drugs can itself alter glycemic outcomes, particularly when treatment withdrawal follows clinical improvement. Previous systematic reviews of carbohydrate-restricted diets have emphasized that medication deescalation frequently accounts for a signiﬁcant share of the observed beneﬁt2. Without considering medication intensity or separating results by treatment modiﬁcation, it is difﬁcult to isolate the direct impact of the diet. Second, individuals assigned to the LCD arm reported a mean rise of about 450 kcal/week in physical activity. This difference carries clinical importance. Metaanalyses show that structured exercise programs reduce HbA1c by roughly 0.67%, while lifestyle advice combined with dietary support yields reductions of about 0.43%3. Physical activity also decreases visceral fat—one of the favorable outcomesin the LCD group. Because the trial was open-label, it is plausible that participants encouraged to follow the LCD also became more engaged in activity. Unless these behavioral shifts are taken into account, improvements may reﬂect exercise effects in addition to dietary change. Future investigations could strengthen causal interpretation by using models that adjust for both medication intensity and activity changes or by performing sensitivity analyses limited to participants without therapy modiﬁcations. These strategies would help clarify the extent to which the LCD itself contributed to the metabolic improvements reported. Respectfully, DISCLOSURE The author declares no conﬂict of interest. Approval of the research protocol: N/A. Informed Consent: N/A. Registry and the Registration No. of the study/trial: N/A. Animal Studies: N/A. DATA AVAILABILITY STATEMENT The data that support the ﬁndings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions. Muhammad Farhan Dow Medical College, Karachi, Pakistan REFERENCES 1. Wang YT, Chen CY, Huang WS, et al. A 90 g/day low-carbohydrate diet improved glycemic control without decreasing frailty in older patients with type 2 diabetes. J Diabetes Investig 2025; 16: 1398–1408. 2. Goldenberg JZ, Day A, Brinkworth GD, et al. Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission: systematic review and meta-analysis. BMJ 2021; 372: m4743. 3. Umpierre D, Ribeiro PA, Kramer CK, et al. Physical activity advice or structured exercise training and association with HbA1c levels in type 2 diabetes: meta-analysis. JAMA 2011; 305: 1790–1799. Doi: 10.1111/jdi.70182 *Correspondence Muhammad Farhan Tel.: +923103980381 E-mail address: [f4rh4n4hm3b@gmail.com](f4rh4n4hm3b@gmail.com) Received 9 September 2025; revised 9 September 2

FAQs

What is the main purpose of this letter?

It addresses and evaluates the findings of Wang et al.’s article on a 90 g/day low-carbohydrate diet in older adults with type 2 diabetes.

Why does the author question attributing benefits solely to carbohydrate restriction?

Medication deescalation occurred substantially in the low-carbohydrate group, and changes in physical activity may also have contributed to glycemic outcomes.

What future analyses does the author propose to strengthen causal interpretation?

Use models adjusting for medication intensity and activity changes, or perform sensitivity analyses limited to participants without therapy modifications.

Sep 28, 2026

Uploaded by Cipher