Can fasting benefit individuals with diabetes?

By Neha MathurReviewed by Lily Ramsey, LLMAug 15 2023

In a recent article published in the Nutrients Journal, researchers conducted an extensive literature search on the PubMed database in September 2022 on fasting and its effect on diabetes to establish the safety and efficacy of fasting as a nutritional therapy for diabetes management.

Study: Efficacy of Fasting in Type 1 and Type 2 Diabetes Mellitus: A Narrative Review. Image Credit: Marcin Malicki/Shutterstock.com

Background

The prevalence of both type 1 (T1DM) and type 2 diabetes mellitus (T2DM) is increasing globally. Studies estimate that diabetes might grip 578 and 700 million people by 2030 and 2045, respectively.

Three main symptoms characterize T2DM, insufficient insulin secretion, excessive glucagon secretion, and insulin resistance (IR). People affected by T2DM often have elevated body weights which deteriorates their insulin sensitivity.

Studies have demonstrated that fasting is beneficial for healthy as well as diseases individuals, especially those with metabolic disorders, such as diabetes. It raised interest among researchers to study its impact on glycemia and its short- and long-term complications.

With an increasing need for a multifaceted approach to diabetes management, primarily weight management through individualized interventions, researchers highly recommend fasting.

Fasting-induced energy deficit could help with permanent weight loss in people with T2DM. Fasting could also enhance glucose tolerance and insulin sensitivity in obese individuals at higher risk of progressing to T2DM.

Likewise, studies evaluating the effects of fasting in people with T1DM have fetched positive results. They have shown how fasting reduces the need for exogenous insulin and total carbohydrate intake, besides stabilizing glycemia and body mass index (BMI).

However, data on how safe fasting is, particularly regarding the risk of hypoglycemia and diabetic ketoacidosis (DKA) in diabetic people, is limited.

About the study

In the current review, researchers evaluated whether fasting could safely and effectively complement pharmaceutical interventions in T1DM and T2DM patients. In the pursuit, they retrieved 27,485 citations from the PubMed database but considered only 97 references for this review.

Results

Even though the evidence base is less robust, the authors noted some substantial benefits of fasting on T1DM and T2DM patients in this study. In patients with T1DM, fasting exhibited the potential to minimize the risk of hypoglycemia, lower glycaemic variability, and improve fat metabolism.

The therapy of T1DM adjusts glycemia with exogenous insulin, dietary changes, and exercise. However, in longstanding T1DM cases, IR to exogenous insulin worsens, leading to excessive gain in body weight.

So, when fasting in T1DM, insulin adjustments should be carefully accounted for. Ideally, the time spent in hypoglycemia must remain unaffected/reduced, especially in children with T1DM, or their hemoglobin A1c levels (HbA1c) could fall after fasting.

While fasting could positively affect metabolism, it adversely affects body composition and the cardiometabolic system. Uncontrolled fasting might also lead to kidney damage in people with T1DM.

During Ramadan fasting (RF), the frequency of severe hypoglycemia in people with T1DM increases compared to other months (0.14 episodes vs. 0.03 episodes per month).

So, people with T1DM who do RM fasting should be well aware of diabetes self-management principles; for instance, they could do continuous glucose monitoring (CGM) to identify hyper/hypoglycemic episodes and adjust their medication accordingly to avoid complications.

Fasting could be applied as an intervention in people with pre-diabetes, which in most cases, leads to the development of T2DM. Targeted lifestyle and weight loss interventions are very beneficial in pre-diabetes management.

In people with T2DM, the timing of food intake and the duration of fasting are paramount for weight management and the accompanying improvement in metabolic health.

However, care when combining medications for T2DM, metformin, GLP-1Ras, or SGLT-2, with fasting, unless their dosage is appropriately adjusted, they pose a potential risk, especially regarding hypoglycemia.

Conclusions

The current review showed that individuals with T1DM and T2DM may fast without worrying about severe glycaemic disturbances.

However, it is efficient as adjuvant therapy for diabetes when performed with utmost care to monitor glucose levels with the support of treating clinicians. These considerations are of utmost importance for diabetic people who fast over a prolonged time, e.g., Muslims who fast during Ramadan.

They could use closed-loop systems with CGM to adjust insulin delivery in real-time to maintain stable blood glucose levels and reduce the risk of hypoglycemia during fasting.

Future studies might capture the long-term effects of fasting using different methodologies in pursuit of evidence of the benefits of fasting in people with T1DM and T2DM.