Introduction

Diabetes mellitus is the most common chronic metabolic disease characterized by blood glucose evaluation; commonly divided into two types of insulin-dependent (type 1 diabetes mellitus, T1DM) and non-insulin-dependent (type 2 diabetes mellitus, T2DM). T2DM is far more prevalent than the others. The overall prevalence of diabetes has dramatically increased over the past two decades, and it was estimated to be increased to more than 552 million by 2030 globally. The prevalence of diabetes is estimated at more than 32.8 million in the Middle East and North Africa by 2011, and it will probably reach more than 60 million by 2030 (Whiting et al., 2011). In Iran, the prevalence of diabetes has been reported at 4.6 million in 2011, which is expected to be 8.3 million in 2030 (Hasan et al., 2020, Whiting et al., 2011, Zabetian et al., 2013). Short-term and long-term complications of diabetes include increased risk of myocardial and cerebrovascular diseases, renal failure, retinopathies, and organs amputation (Zheng et al., 2018).
Nowadays, sweeteners are commonly used as food additives. As a natural sweetener, sucrose causes some health problems, such as blood pressure, heart diseases, tooth decay, obesity, increasing blood glucose, and insulin levels (Bruun et al., 2015, Fowler, 2016, Nourmohammadi et al., 2011). In addition to sweetening usage, poly-alcohols low-calorie ketosis like sorbitol, mannitol, and erythritol have blood glucose reduction and anti-oxidative ability. Erythritol reduces blood glucose by reducing glucose intake of the intestine, increasing muscle glucose uptake, and strengthening glucose metabolizing enzymes (Chukwuma et al., 2018, De Cock, 2018, Yokozawa et al., 2002).
A new sweetener with the commercial name of lacritose is a combination of four simple sugars (lactose, fructose, sucrose, and erythritol), prepared with specific ingredients and percentages. This natural sweetener contains fewer calories and also has an appropriate taste for diabetic patients (Mohsenpour et al., 2019).
 However, the glycemic response of diabetic patients to this sweetener is not clear yet. Since this is made up of four natural sugars; its glycemic response and probable long-term gastrointestinal complications are discussed. The present study investigated the effect of this sweetener on blood glucose level and possible reactions and difficulties in people with T2DM.
Materials and Methods
Study design and participants: In the current randomized clinical trial, 52 types 2 diabetic patients referred to Yazd Diabetes Research Center were randomly assessed for eligibility. The sample size was calculated by a randomized blocking method. Considering type 1 error 0.05, effect size 0.55, and the power of 80%. The estimated sample size was 10 participants in each group. Also, 15 % was added for the attrition rate. The final sample size was 30 participants in each group.
Then 30 patients were qualified to participate in the study (after being aware of the process and completing the consent form). They were divided into three groups were randomly included in two intervention groups and a control group. Participant groups, researchers, and analyzers were not aware of the type of sugar consumption in the groups.
The inclusion criteria were: 1. Having type 2 diabetes, 2. The age group of 30-60, 3. Fasting blood glucose (FBG) of less than 200 mg/dl, 4. 7% ≤ HbA1C ≤ 9% 5. Being under the control of diet or edible medications, 6. The existence of sugar and sweeteners in the diet, 7. Having a medical file at Yazd Diabetes Research Center, and 8. Willingness to participate in the study.
The exclusion criteria were: 1. Being under the treatment of insulin, 2. Unable to follow up (living in another city), 3. The necessity of severe blood glucose control due to the complications of diabetes, 4. Significant changes in their blood glucose and blood pressure level over the past month, 5. Considerable change in their blood lipids profile over the past month, 6. A remarkable change in their caloric volume intake and their activity, 7. History of lactic deficiency, 8. Pregnancy and lactation, 9. Patients with severe infection or endocrine disorders, 10. Patients with hepatic and renal failure, 11. Patients with diabetes complications (nephropathy, neuropathy, retinopathy), 12. Patients with a body mass index (BMI) higher than 35 kg/m².
The research center paid all relevant test costs during the two weeks of the study. After blood sampling and measurements, the total number of participants (n=30) were divided into control, group 1, and group 2 based on randomized block design.
The control group was prescribed only sucrose (SG), up to the maximum permissible dose of sucrose every day base on an individual's BMI; a man with 70 kg body weight can consume 92 g/day of lacritose. Half of the maximum permissible dose of sucrose plus decreased volume equivalent of lacritose for lacritose group (LG), and lacritose as equivalent to the top dose level of sucrose for lacritose plus sucrose (LSG) after calculating the maximum permissible dose of sucrose were prescribed. The maximum permitted dose was considered for each participant by the estimated energy requirement equation considering the individual’s BMI, age, and blood glucose level.
During two weeks, they were followed every three days and were asked about sweetener consuming details and possible complications. Then, after two weeks, when they referred to the center again, they were gone under the blood sampling tests, and the measurements, such as gastrointestinal complications were taken.
 Measurements: Factors included baseline characteristics (age, gender, weight, and height), duration of diabetes, BMI, fasting blood glucose (FBG), fructose amine, hemoglobin A1C (HbA1C), 2-hour postprandial test (2HPP), serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), SGOT/SGPT ratio, urea, creatinine, insulin resistance index (HOMA-IR), and gastrointestinal complications.
HbA1C and fructose amine factors reflect the glycemic level in controlling the blood glucose level. 2HPP is a valid diagnostic test that measures the serum glucose level after 2 hours of the breakfast meal (Beck et al., 2011). Also, SGOT, SGPT, and SGOT/SGPT ratio are hepatic diagnostic tests used to assay the hepatic effects (Baygi et al., 2017, Lee and Yang, 2013).
Ethical considerations: This research was presented to the ethics committee of Shahid Sadoughi University of Medical Sciences and approved by the internal medicine department. The ethics committee approved the study with the number IR.SSU.REC.1396.102 on August 15, 2017. The patients were informed about the objective and nature of the study, and each participant provided written consent before the study begins. The trial was registered at the Iranian registry of clinical trials (www.irct.ir) with ID code IRCT2017102418858N7.
Safety of lacritose: The organoleptic and microbial tests of lacritose have been performed by Laboratory of Food and Drug Administration of Yazd province and Pasargad laboratory in Tehran province. Its low-calorie content has already been approved by Pasargad laboratory, Yazd, Iran. Each 100 g of lacritose consisted of 27.4 g of lactose, 12.9 g of fructose, 5.57 g of sucrose, and 54.13 g of erythritol. Its glycemic index was 19.72, and it had about 1.98 kcal/g energy (Mohsenpour et al., 2019)
Data analysis: For numerical variables, descriptive statistics were presented as mean ± standard deviation (Mean ± SD). The data were analyzed by ANOVA test for parametric factors and Kruskal-Wallis test for non-parametric factors. To assess the results normality, Kolmogorov-Smirnov statistical test was used. A P-value of less than 0.05 was considered significant.
Results
Thirty patients participated in this study, including 17 (56.6%) male and 13 (43.4%) female with the mean age of 53.6 ± 5.57 (minimum and maximum ages were 38 and 60 years old).
Baseline of factors is presented in Table 1. All of the factors did not considerably vary among the groups (P > 0.05). Noteworthy, FBG significantly decreased in the two lacritose groups (LG; P <0.001, LSG; P = 0.04), while increased in the SG (mean differences: 19.00 ± 55.60 mg/dl). TG and Micro-albuminuria had unimportant reduction in LG (P = 0.36 and P = 0.16,) and LSG (P = 0.65 and P = 0.22, respectively), although in SG increased (mean differences: 8.10 ± 58.32 mg/dl, 3.40 ± 8.18 mg/g creatinine; P = 0.67 and P = 0.22). LSG and SG showed an elevation in SGPT (mean differences: 1.80 ± 22.52 u/l, 3.60 ± 8.46 u/l), SGOT (mean differences: 3.30 ± 20.91 u/l, 1.00 ± 6.00 u/l), and HOMA-IR (mean differences: 0.59 ± 2.95, 1.78 ± 3.01) compared to LG; no significant difference was observed in the results of the groups (P = 0.05). Also, intergroup change in HOMA-IR was significant (P = 0.01, Table 1).
Creatinine decreased in the LSG, but it was not significant (mean differences: -0.04 ± 0.08, P = 0.16) and increased in the LG and SG (mean differences: 0.04 ± 0.13 mg/dl, 0.01 ± 0.13 mg/dl, P = 0.37 and P = 0.82). Total cholesterol significantly reduced in the LSG (mean differences: -36.40 ± 44.95 mg/dl, P = 0.03) compare to the increase in the LG and SG, but it was not significant (mean differences: 3.14 ± 16.26 mg/dl, 6.20 ± 22.61 mg/dl, P = 0.52 and P = 0.40).  Level of 2HPP after consuming all sugar mixtures decreased in all groups; although the changes in the LG was significant (P = 0.04), intergroup variety was not significant (P = 0.49). Fructose amine reduction was different in the LSG and SG (mean differences: -0.20 ± 0.34 µmol/l, -0.18 ± 0.86 µmol/l; P = 0.83, P= 0.52).