Diabetic Medication Adjustment for Low Carb Diets

How to manage diabetic medication adjustment when low carb diets lead to improved clinical outcomes.

Lifestyle modifications have been associated with improvements in type 2 diabetes, with the possibility of remission. Recent research shows that low carb diets are an effective lifestyle modification in patients with diabetes, with minimal side effects. Patients on this diet see improvements in diabetes management and may have a reduced need for hypoglycemic agents, resulting in lower drug costs. Providers need to stay up to date with medication management for patients on low carb diets. After the initiation of a low carb diet, patients with diabetes usually see a drastic reduction in blood glucose levels, and this study provides expert advice on how to manage medication reductions in this situation.

A low carb diet is defined as <130 grams of digestible carbohydrates per day. These carbohydrates are recommended to be high in fiber and low in glycemic index. The recommendations within this study are derived from experience, expert opinion, and the pharmacodynamics of the drug. Although this study only evaluated diabetic medications, providers should also note that antihypertensives may need to be reduced for patients on a low carb diet. Three clinical outcomes were assessed for the safety and suitability of hypoglycemic agents in combination with a low carb diet as follows:  risk of hypoglycemia, degree of carbohydrate restriction, and weighing the benefits and side effects.

Diabetic medications pose various issues depending on drug class; some of the risks include hypoglycemia and ketoacidosis. Since sulfonylurea and meglitinides increase the risk of hypoglycemia, they should be stopped or reduced when the patient is strictly adhering to a low carb diet. The initial dose reduction should be a minimum of 50%, with expected future decreases. Patients may temporarily experience hyperglycemia during the transition.

For patients with type 2 diabetes, practical expertise suggests a 50% reduction in daily insulin dose at the initiation of this diet. The exception is for patients with a markedly elevated HbA1c; in this case, a more conservative 30% insulin reduction is recommended at diet initiation. Specifically, patients on a basal-bolus regimen will need to reduce or stop the bolus insulin significantly altogether. For patients on mixed or basal insulin alone, it is recommended to minimize each dose by 30-50% at the start of this diet. Some patients will eventually stop insulin altogether as their insulin resistance improves. Complete cessation of insulin is not possible in patients with latent autoimmune diabetes of adults or type 1 diabetes, but clinical improvements and insulin reductions are possible on a low carb diet.

Numerous diabetic drugs pose no additional risk when used in combination with a low carb diet. These include metformin, GLP-1 agonist, thiazolidinediones, DPP-4 inhibitors, and acarbose. Metformin is not only safe to continue but may also offer other favorable benefits. This trend is also seen with GLP-1 agonists; keeping this drug class offers increased satiety and possible cardiovascular benefits. However, patients should be able to stop using their GLP-1 agonist while adhering to this diet if the pros do not outweigh the cons. DPP-4’s can be used in combination from a safety standpoint, but cessation is suggested since they offer minimal benefit for a patient on a low carb diet. Acarbose may be continued, but since the patient will be consuming a reduced amount of carbohydrates, it is not necessary to continue this drug.

Conversely, thiazolidinediones are not recommended in combination with this diet and should be stopped once the patient has glucose improvements. Due to an increased risk for ketoacidosis, SGLT2 inhibitors are not recommended for use on a low carb diet and should be stopped at the initiation.

Low carb diets are becoming very popular and lead to improved clinical outcomes in patients with diabetes. Therefore, providers should understand how to manage hypoglycemic agents under these conditions to ensure safe and effective treatment. It is vital that patients self-monitor blood glucose and report the results to their provider during this transition for proper medication management.

Practice Pearls:

• Low carb diets are an effective lifestyle modification in patients with diabetes, with minimal side effects.
• At initiation of a low carb diet: SGLT2-inhibitors should be stopped, sulfonylureas and meglitinides should be significantly reduced or stopped, insulins should be reduced, metformin and GLP-1 agonist are safe to continue with possible added benefits, thiazolidinediones are only safe to continue temporarily, and acarbose and DPP-4 inhibitors provide minimal benefit on this regiment.
• Providers must be competent in adjusting these medications to provide safe care on a low carb diet.

References for: “Diabetic Medication Adjustment for Low Carb Diets”:
Unwin, D., Cavan, D., Cucuzzella, M., Patel, M., & Campbell Murdoch. (2019, July 01). Adapting diabetes medication for low carbohydrate management of type 2 diabetes: A practical guide. Retrieved from https://bjgp.org/content/69/684/360

Cardiovascular disease and risk management. Diabetes Care 2017;40(Suppl S75-87.doi:10.2337/dc17-S012

Kassey James, Pharm.D.Candidate, LECOM School of Pharmacy

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