Dietary carbohydrate restriction augments weight loss-induced improvements in glycaemic control and liver fat in individuals with type 2 diabetes: a randomised controlled trial.
Plain language summary
The carbohydrate restricted diet has been shown to be beneficial for Type 2 diabetes (T2D) management and reducing cardiovascular disease risk. This open-label, parallel randomised controlled trial involved Type 2 diabetic patients taking antidiabetic medications who restricted their energy intake by following either a carbohydrate-reduced high protein diet or a conventional diabetic diet. Participants in both groups had a 5.9% reduction in body weight, similar changes in fasting NEFA, apoB, apoA-1, total cholesterol, LDL-cholesterol, HDL-cholesterol, and non-HDL cholesterol, and a significant reduction in fasting glucose, insulin, C-peptide, and HOMA2-IR after 6 weeks of intervention. Carbohydrate-reduced high protein diet group showed a greater reduction in HbA1c and diurnal mean glucose, glycaemic variability, fasting triacylglycerol concentration and liver fat content. Carbohydrate-reduced high protein diet caused an adverse reaction in some patients, and those following a carbohydrate-reduced high protein diet excreted more urea than those eating a conventional diabetic diet. To confirm the results of this study, long-term robust studies are needed. This study can assist healthcare professionals in understanding the benefits of following a carbohydrate-reduced high protein diet in improving glycaemic control, triglyceride levels, and reducing body weight in Type 2 diabetes patients.
AIMS/HYPOTHESIS Lifestyle modification and weight loss are cornerstones of type 2 diabetes management. However, carbohydrate restriction may have weight-independent beneficial effects on glycaemic control. This has been difficult to demonstrate because low-carbohydrate diets readily decrease body weight. We hypothesised that carbohydrate restriction enhances the beneficial metabolic effects of weight loss in type 2 diabetes. METHODS This open-label, parallel RCT included adults with type 2 diabetes, HbA1c 48-97 mmol/mol (6.5-11%), BMI >25 kg/m2, eGFR >30 ml min-1 [1.73 m]-2 and glucose-lowering therapy restricted to metformin or dipeptidyl peptidase-4 inhibitors. Participants were randomised by a third party and assigned to 6 weeks of energy restriction (all foods were provided) aiming at ~6% weight loss with either a carbohydrate-reduced high-protein diet (CRHP, percentage of total energy intake [E%]: CH30/P30/F40) or a conventional diabetes diet (CD, E%: CH50/P17/F33). Fasting blood samples, continuous glucose monitoring and magnetic resonance spectroscopy were used to assess glycaemic control, lipid metabolism and intrahepatic fat. Change in HbA1c was the primary outcome; changes in circulating and intrahepatic triacylglycerol were secondary outcomes. Data were collected at Copenhagen University Hospital (Bispebjerg and Herlev). RESULTS Seventy-two adults (CD 36, CRHP 36, all white, 38 male sex) with type 2 diabetes (mean duration 8 years, mean HbA1c 57 mmol/mol [7.4%]) and mean BMI of 33 kg/m2 were enrolled, of which 67 (CD 33, CRHP 34) completed the study. Body weight decreased by 5.8 kg (5.9%) in both groups after 6 weeks. Compared with the CD diet, the CRHP diet further reduced HbA1c (mean [95% CI] -1.9 [-3.5, -0.3] mmol/mol [-0.18 (-0.32, -0.03)%], p = 0.018) and diurnal mean glucose (mean [95% CI] -0.8 [-1.2, -0.4] mmol/l, p < 0.001), stabilised glucose excursions by reducing glucose CV (mean [95% CI] -4.1 [-5.9, -2.2]%, p < 0.001), and augmented the reductions in fasting triacylglycerol concentration (by mean [95% CI] -18 [-29, -6]%, p < 0.01) and liver fat content (by mean [95% CI] -26 [-45, 0]%, p = 0.051). However, pancreatic fat content was decreased to a lesser extent by the CRHP than the CD diet (mean [95% CI] 33 [7, 65]%, p = 0.010). Fasting glucose, insulin, HOMA2-IR and cholesterol concentrations (total, LDL and HDL) were reduced significantly and similarly by both diets. CONCLUSIONS/INTERPRETATION Moderate carbohydrate restriction for 6 weeks modestly improved glycaemic control, and decreased circulating and intrahepatic triacylglycerol levels beyond the effects of weight loss itself compared with a CD diet in individuals with type 2 diabetes. Concurrent differences in protein and fat intakes, and the quality of dietary macronutrients, may have contributed to these results and should be explored in future studies. TRIAL REGISTRATION ClinicalTrials.gov NCT03814694. FUNDING The study was funded by Arla Foods amba, The Danish Dairy Research Foundation, and Copenhagen University Hospital Bispebjerg Frederiksberg.
The effect of periodic ketogenic diet on newly diagnosed overweight or obese patients with type 2 diabetes.
BMC endocrine disorders. 2022;22(1):34
Plain language summary
Currently, the ketogenic diet is gaining popularity in managing Type 2 diabetes (T2D). Ketogenic diets replace carbohydrates with fat and include limited carbohydrates and adequate protein. This randomised controlled trial evaluated the effects of the 12-week ketogenic diet on sixty overweight or obese T2D patients. Both the ketogenic and control diabetes diet groups achieved significant reductions in weight, body mass index, waist circumference, triglycerides, total cholesterol, low-density lipoprotein, high-density lipoprotein, fasting blood glucose, fasting insulin, and HbA1c. However, the ketogenic group showed significantly greater reductions in body mass, blood lipids, and blood glucose than the control group. In the ketogenic diet group, serum uric acid levels were higher than those in the control diet group. It was found that the control diet group adhered to the diet for a longer period than the ketogenic diet group, whose willingness to adhere to the diet long-term was weaker. More robust long-term studies are needed to evaluate the long-term effects of a ketogenic diet. In this study, more patients who followed the ketogenic diet experienced hypoglycaemic events during the first four weeks. Healthcare providers should exercise caution when recommending a short term therapeutic ketogenic diet.
BACKGROUND The ketogenic diet (KD) is characterized by fat as a substitute of carbohydrates for the primary energy source. There is a large number of overweight or obese people with type 2 diabetes mellitus (T2DM), while this study aims to observe periodic ketogenic diet for effect on overweight or obese patients newly diagnosed as T2DM. METHODS A total of 60 overweight or obese patients newly diagnosed as T2DM were randomized into two groups: KD group, which was given ketogenic diet, and control group, which was given routine diet for diabetes, 30 cases in each group. Both dietary patterns lasted 12 weeks, and during the period, the blood glucose, blood lipid, body weight, insulin, and uric acid before and after intervention, as well as the significance for relevant changes, were observed. RESULTS For both groups, the weight, BMI(body mass index), Waist, TG (triglyceride), TC(cholesterol), LDL (low-density lipoprotein cholesterol), HDL (high-density lipoprotein cholesterol), FBG (fasting glucose), FINS (fasting insulin), HbA1c (glycosylated hemoglobin) were decreased after intervention (P < 0.05), while the decrease rates in the KD group was more significant than the control group. However, UA(serum uric acid) in the KD group showed an upward trend, while in the control group was not changed significantly (P > 0.05).The willingness to adhere to the ketogenic diet over the long term was weaker than to the routine diet for diabetes. CONCLUSION Among the overweight or obese patients newly diagnosed as type 2 diabetes mellitus, periodic ketogenic diet can not only control the body weight, but also control blood glucose and lipid, but long-term persistence is difficult.
The Effect of Low-Carbohydrate Diet on Glycemic Control in Patients with Type 2 Diabetes Mellitus.
Plain language summary
Dietary intervention is a strategy to manage diabetes mellitus, as it can reduce the burden on islet cells and thus improve blood glucose levels, lipid profiles, and cognitive status. The aim of the study was to find out the effectiveness of the ‘six-point formula’ and the effects of a low-fat diet and low-carbohydrate diet on hyperglycaemia. The study is a prospective, single-blind randomized controlled trial which recruited 56 participants with type 2 diabetes mellitus. The participants were randomly allocated to receive either a low-fat diet or a low-carbohydrate diet. Results show that HbA1c levels (the average blood glucose levels in the last 2 – 3 months) in low-carbohydrate diet decreased significantly compared to the low-fat diet. The body mass index and the total cholesterol levels of the participants following the low-carbohydrate diet also decreased. Authors conclude that a low-carbohydrate diet can improve blood glucose, regulate blood lipids, reduce body mass index and decrease insulin doses more than a low-fat diet in Chinese patients with type 2 diabetes mellitus.
OBJECTIVE In China, a low-fat diet (LFD) is mainly recommended to help improve blood glucose levels in patients with type 2 diabetes mellitus (T2DM). However, a low-carbohydrate diet (LCD) has been shown to be effective in improving blood glucose levels in America and England. A few studies, primarily randomized controlled trials, have been reported in China as well. METHOD Firstly, we designed two 'six-point formula' methods, which met the requirements of LCD and LFD, respectively. Fifty-six T2DM patients were recruited and randomly allocated to the LCD group (n = 28) and the LFD group (n = 28). The LCD group received education about LCD's six-point formula, while the LFD group received education about LFD's six-point formula. The follow-up time was three months. The indicators for glycemic control and other metabolic parameters were collected and compared between the two groups. RESULTS Forty-nine patients completed the study. The proportions of calories from three macronutrients the patients consumed met the requirements of LCD and LFD. Compared to the LFD group, there was a greater decrease in HbA1c level in the LCD group (-0.63% vs. -0.31%, p < 0.05). The dosages of insulin and fasting blood glucoses (FBG) in the third month were lower than those at baseline in both groups. Compared with baseline values, body mass index (BMI) and total cholesterol (TC) in the LCD group were significantly reduced in the third month (p < 0.05); however, there were no statistically significant differences in the LFD group. CONCLUSIONS LCD can improve blood glucose more than LFD in Chinese patients with T2DM. It can also regulate blood lipid, reduce BMI, and decrease insulin dose in patients with T2DM. In addition, the six-point formula is feasible, easily operable, and a practical educational diet for Chinese patients with T2DM.