**2. Restricted carbohydrate diet and its physiological and metabolic effects**

#### **2.1 Therapeutic restricted carbohydrate**

Therapeutic carbohydrate restriction lowers fasting and postprandial blood glucose and insulin levels while also reducing insulin resistance. All of these changes can improve metabolic syndrome markers [21]. In insulin resistance, it is harder for the body to maintain normal blood glucose leading to type 2 diabetes. Thus, it is counterproductive to consume carbohydrates that digest down into significant amounts of glucose [16].

As predicted by the glycemic index, restricting any foods that break down into glucose lowers blood glucose levels and insulin secretion. This includes whole-grain starches and high-sugar fruits. A glucometer can easily track blood glucose levels at home or in a clinical setting. A glucometer is an essential tool for identifying foods that raise blood glucose levels, even for people who do not have diabetes. We recommend that patients monitor their glucose levels when starting TCR if possible.

#### **2.2 Insulin**

The main reason for monitoring blood glucose levels may have less to do with glucose and more with insulin. Carbohydrates in the diet raise blood sugar levels and stimulate insulin secretion. While this is a normal physiological response, it can negatively affect health. Insulin maintains homeostasis by transporting glucose into cells and inhibiting glucose production in the liver when blood glucose levels rise. This is a life-saving response because it prevents dangerously high glucose levels in the blood.

On the other hand, insulin has other functions that we, as clinicians, frequently overlook. Insulin, for example, prevents the body from burning fat for energy instead of encouraging fat storage [22]. As a result, higher insulin levels can be a problem for people trying to lose weight. Giving insulin to people with type 2 diabetes can set off a vicious cycle of weight gain and insulin resistance.

Genetics, environment, and lifestyle all play a role in how well someone manages their dietary carbohydrate intake. Insulin levels rise and can remain chronically elevated when people consume more carbohydrates than their bodies can handle, known as hyperinsulinemia [23]. When this happens, the body's response to insulin signals becomes ineffective. Insulin resistance is the term used to describe this condition [24].

The development of the metabolic syndrome and an increased risk of heart disease are strongly linked to hyperinsulinemia and insulin resistance [25]. Insulin resistance is thought to be a common underlying mechanism for various chronic diseases, including type 2 diabetes, hypertension, atherogenic dyslipidemia, and chronic inflammation [26].

We tend to use glucose levels as a proxy for insulin levels because point-of-care insulin meters are unavailable. However, it's important to note that just because glucose levels are normal does not mean insulin levels are as well. Glucose levels may be normal in the early stages of diabetes and metabolic syndrome because high insulin levels keep them there.

Restriction of carbohydrate intake, fortunately, is an effective way of addressing the root cause of hyperinsulinemia and insulin resistance.

## **3. Getting the intervention started for metabolic diseases**

This section covers which patients are good candidates for TCR and which patients should be approached with caution when implementing this dietary change. It also explains the importance of baseline assessments and briefly covers pre-diet evaluation and counseling.

#### **3.1 Selection of patients**

Patients with any metabolic syndrome symptoms are ideal candidates for therapeutic carbohydrate restriction. Patients with hypertension, mixed dyslipidemia, hyperglycemia, including type 2 diabetes, or obesity, particularly abdominal obesity, fall into this category.

*Treating Type 2 Diabetes with Therapeutic Carbohydrate Restriction DOI: http://dx.doi.org/10.5772/intechopen.107184*

#### **3.2 Exclusion criteria**


#### **3.3 The necessity for caution**

It's uncommon to come across someone completely against therapeutic carbohydrate restriction. You'll often come across a patient who will benefit from TCR but who will require more attention and caution from you.

#### **3.4 Risks associated with a low carbohydrate diet**

A study published in May 2018 followed over 2000 men for over 20 years and found that higher protein intake was slightly associated with a higher risk of heart failure [27]. However, not all associations reached statistical significance, and some confidence intervals crossed zero. The long-term effects of a low carbohydrate diet are largely unknown. There has been a concern raised by some studies about a high protein intake increasing the risk of renal stones. However, a low carbohydrate diet only needs to contain a normal amount of protein. Thus a low carbohydrate diet is not known to worsen renal function, and some studies have shown an association with an improvement in eGFR.

In August 2018, a paper was published suggesting an increase in mortality for those who ate a low carbohydrate diet, in which carbohydrates were replaced with animal proteins, in contrast to those who replaced carbohydrates with plant-derived protein [28]. Those who developed diabetes during the study were excluded from follow-up, which may limit the applicability of this study to the diabetic patients at whom this chapter is aimed. If patients ask about this study (which has been extensively covered in the media), it would be reasonable to suggest that their diet remains balanced even when carbohydrates are reduced with proteins coming from plant and animal sources.

#### *3.4.1 Diabetes type 2*

As evidence shows, therapeutic carbohydrate restriction is a valuable intervention for patients with type 2 diabetes. Patients with diabetes, particularly those taking glucose-lowering medications, must be able to use a blood glucose meter and communicate their results to their health care team quickly [29].

To avoid hypoglycemic episodes and ensure patient safety, you as a healthcare provider must be more vigilant with patients with type 2 diabetes.

#### *3.4.2 Hypertension*

For patients with hypertension, therapeutic carbohydrate restriction is also an effective intervention. On the other hand, these patients must be able to monitor their blood pressure at home and communicate with their healthcare providers quickly to adjust antihypertensive medications appropriately. Remember that your team is critical in assisting the patient in avoiding symptomatic hypotension.

#### *3.4.3 Gallbladder removal*

Therapeutic carbohydrate restriction may still be a promising intervention for patients with gallbladders removed. When teaching these patients what foods to eat, tell them to gradually increase the amount of fat in their diet to avoid diarrhea. However, most patients without a gallbladder can successfully follow TCR after a slow transition period.

#### *3.4.4 Chronic kidney disease*

Due to the misconception that these diets are "high protein diets," there is often concern about using therapeutic carbohydrate reduction in patients with decreased kidney function. In reality, protein accounts for no more than 30% of calories in TCR diets. Except for those with pre-existing, advanced renal failure, this level is likely safe.

There is no evidence that protein intake at levels commonly consumed during TCR is harmful to people with mildly or moderately reduced kidney function [30], and plenty of evidence demonstrates its safety.

#### *3.4.5 Kidney stones*

When starting TCR, patients predisposed to kidney stones may increase their risk. In particular, uric acid levels in the blood can rise, increasing the risk of uric acid kidney stones in susceptible people. Patients with kidney stones should stay hydrated by following general guidelines. Experienced clinicians have discovered that encouraging adequate amounts of sodium, potassium, and, most importantly, magnesium can help reduce the risk of kidney stones. We should advise patients who have had calcium oxalate stones, the most common type of kidney stone, to avoid high oxalate foods like spinach, almonds, and cashews. TCR is completely safe in patients who have had kidney stones.

#### *3.4.6 Gout*

Patients prone to gout have the same concerns as those prone to uric acid kidney stones. As previously mentioned, uric acid levels can rise in the early stages of TCR. This can trigger a gout flare-up in susceptible individuals, though gout may improve over time on a carbohydrate-restricted diet [31]. These patients should drink plenty of water and get plenty of sodium, potassium, and magnesium. Another option for those prone to frequent attacks is to use prophylactic allopurinol during the early stages of the intervention.

#### *3.4.7 Breastfeeding and pregnancy*

When it comes to TCR, pregnancy and breastfeeding must be considered. Although moderate carbohydrate restriction has long been used to treat pregnant women with gestational diabetes [32], carbohydrates are rarely restricted to the very low levels used for weight loss or type 2 diabetes treatment. The amount of

*Treating Type 2 Diabetes with Therapeutic Carbohydrate Restriction DOI: http://dx.doi.org/10.5772/intechopen.107184*

carbohydrate restriction should be individualized for the patient based on her medical history, but it should usually be at least 50 grams per day. According to a few case reports in the medical literature, more aggressive carbohydrate restriction during pregnancy or breastfeeding may increase the risk of ketoacidosis [33]. Fresh vegetables, meat, fish, eggs, dairy, nuts, seeds, and a small amount of fruit, on the other hand, provide adequate essential nutrition for both mother and baby.

#### **3.5 Baseline tests**

All TCR patients should have baseline and follow-up assessments to screen for potential harm and document successful progress.

To begin, keep track of each patient's starting weight. Even though it provides less detailed information, waist circumference is the simplest method. Furthermore, it is simple for patients to notice if their pants have suddenly become looser. Another critical vital sign, especially for those taking antihypertensives, is baseline blood pressure. Keep in mind that medications will almost certainly need to be adjusted once a patient begins TCR.

#### **3.6 Lab tests**

We recommend running the following baseline lab tests when starting a patient on TCR.


Although there is no universally accepted reference range for fasting insulin, we can use the literature to help us develop useful ranges.

One study [35] found that levels above 25 micro IU/ml were associated with a very high risk of developing prediabetes, and levels above 12 were associated with a moderate risk, confirming an earlier study. In a later study, it was discovered that insulin levels above 8 micro IU/ml c orrectly predicted prediabetes in 80% of the people tested [35].

Furthermore, one study claimed that a HOMA-IR of less than 1.6 was a normal values [36].

• **Fasting lipid profile**: A baseline fasting lipid panel is recommended for everyone because mixed dyslipidemia is common in metabolic syndrome. We expect highdensity lipids (HDL) to rise and triglycerides to fall due to TCR. We also need to keep an eye on LDL-C levels, as this is likely the first area of concern with TCR. While some guidelines recommend non-fasting panels to improve compliance, this makes interpreting triglycerides more difficult because their value is dependent on the content and timing of the most recent meal. As a result, fasting lipid panels are recommended for consistency.
