Low-Carbohydrate and Ketogenic Dietary Patterns for Type 2 Diabetes Management

Emerging Strategies

Emerging strategies, such as continuous glucose monitors (CGMs) and the use of intermittent fasting/time-restricted eating (TRE), can be used with the LC diet to help improve the monitoring and management of T2DM. In the recently published VA/DoD guidelines for T2DM, the work group suggested real-time CGMs for qualified patients with T2DM.⁴ These include patients on daily insulin who are not achieving glycemic control or to reduce the risk for hypoglycemia. CGMs have shown evidence of improved glycemic control and decreased hypoglycemia in those with T2DM.^38,39 It is currently unknown if CGMs improve long-term glycemic control, but they appear promising for managing and reducing medications for those on an LC diet.⁴⁰

TRE can be supplemented with an LC plan that incorporates “eating windows.” Common patterns include 14 hours of fasting and a 10-hour eating window (14F:10E), or 16 hours of fasting and an 8-hour eating window (16F:8E). By eating only in the specified window, patients generally reduce caloric intake and minimize insulin and glucose excursions during the fasting window. No changes need to be made to the macronutrient composition of the diet, and LC approaches can be used with TRE. The mechanism of action is likely multifactorial, targeting hyperinsulinemia and insulin resistance as well as producing a caloric deficit to enable weight loss.⁴¹ Eating windows may improve insulin sensitivity, reduce insulin resistance, and enhance overall glycemic control. The recent VA/DoD guidelines recommended against intermittent fasting due to concerns over the risk of hypoglycemia despite larger weight loss in TRE groups.⁴ Recently, a study using CGMs and TRE demonstrated both improved glycemic control and no hypoglycemic episodes in patients with T2DM on insulin.⁴² Patients who would like to supplement TRE with an LC plan as a strategy for improved glycemic control should work closely with their PACT to help manage their TRE and LC plan and consider a CGM adjunct, especially if on insulin.

Barriers

Managing T2DM often requires comprehensive lifestyle modifications of nutrition, exercise, sleep, stress management, and other psychosocial issues, as well as an interdisciplinary team-based approach.⁴³ The advantage of working within the VA includes a uniform system within a network of care. However, many patients continue to use both federal and private health care. This use of out-of-network care may result in fragmented, potentially disjointed, or even contradictory dietary advice.

The VA PACT, whole health for holistic health, and weight loss interventions such as the MOVE! program provide lifestyle interventions like nutrition, physical activity, and behavior change. However, these well-intentioned approaches may provide alternative and even diverging recommendations, which place additional barriers to effective patient management. In patients who are advised and accept a trial of an LC plan, each member of the team should embrace the self-management decision of the patient and support the plan.²⁹ Any conflicts, questions, or concerns should be communicated directly with the team in an interdisciplinary approach to provide a unified message and counsel.

The long-term effects and sustainability of an LC diet have been questioned in the literature.^44-46 Recently, the use of an app-based coaching plan has demonstrated short- and long-term sustainability on an LC diet.⁴⁷ In just 5 months in a large VA system, 590 patients using a virtual coaching platform and a VLCK diet plan were found to have lower HbA_1c levels, reduced diabetic medication fills, lower body mass index, fewer outpatient visits, and lower prescription drug costs.

A 5-year follow-up found nearly 50% of participants sustained a VLCK diet for T2DM. For patients who participated in the study after 2 years, 72% sustained the VLCK diet in years 2 to 5. Most required nearly 50% fewer medications and in those that started with insulin, half did not require it at 5 years.⁴⁸ Further research, however, is necessary to determine the long-term effects on cardiometabolic markers and health with LC diets. There are no long-term RCTs on outcomes data looking at T2DM morbidity or mortality. While there are prospective cohort studies on LC diets in the general population on mortality, they demonstrate mixed results. These studies may be confounded by heterogeneous definitions of LC diets, diet quality, and other health factors.^49-51

Conclusions

The effective use of LC diets within a PACT with close and intensive lifestyle counseling and a safe approach to medication management and deprescribing can improve glycemic control, reduce the overall need for insulin, reduce medication use, and provide sustained weight loss. Additionally, the use of therapeutic carbohydrate reduction and subsequent medication deprescription may lead to sustained remission of T2DM. The current efficacy and sustainment of therapeutic carbohydrate reduction for patients with T2DM appears promising. Further research on LC diets, emerging strategies, and long-term effects on cardiometabolic risk factors, morbidity, and mortality will continue to inform future practice in our health care system.

Acknowledgments

We thank Cecile Seth who has been instrumental in pushing us forward and the Metabolic Multiplier group who has helped encourage and provide input into this article.