Self-monitoring of blood glucose as control tool in the different management contexts for Type 2 Diabetes Mellitus . What is its current role in non-insulin users?

practice guidelines, 7 narrative reviews, 5 meta-analyses, and 1 systematic review. Conclusion: Based on the evidence found in this review it is possible to say that the use of SMBG in patients with T2DM is beneficial and that it has a positive impact on non-insulin users in terms of achieving glycemic control and defining therapeutic changes.


Self-monitoring of blood glucose as control tool in the different management contexts for Type 2 Diabetes Mellitus.
What is its current role in non-insulin users?
Automonitoreo glicémico como herramienta de control en los distintos contextos de manejo para diabetes mellitus tipo 2 ¿Cuál es su rol actual en no-usuarios de insulina?

Introduction
Diabetes mellitus (DM) is usually a silent disease that constitutes one of the most challenging health problems of the 21 st century worldwide.DM prevalence is rapidly increasing, and it has been estimated that by 2 030 approximately 550 million people will be affected by this disease globally.(1) Over the last decades, DM cases prevalence has experienced an increase that exceeds that of any other health condition (2)(3)(4)(5); it can be developed by anyone, regardless of their socioeconomic status, and it has been associated with a decrease in quality of life, for it affects multiple organ systems; also it has been associated with micro and macro-vascular complications.(2-5) Large clinical trials have reported that achieving effective glycemic and metabolic control reduces the incidence of complications related to diabetes and improves its prognosis.(6,7) Taking this into account, self-monitoring blood glucose (SMBG) is a primary tool for diabetes management, making possible the evaluation of the effectiveness of glycemic control, which in turn allows making relevant adjustments regarding the management of the disease.(8)(9)(10) Currently, it is an integral component of intensive insulin therapy in patients with Type 2 DM, as well as in patient education programs.(11)(12)(13) The American Diabetes Association (ADA), the Latin American Diabetes Association (ALAD) and the Canadian Diabetes Association (CDA) support SMBG in Type 1 and Type 2 Diabetes Mellitus (T2DM) patients using insulin since its main benefits include helping to achieve the glycosylated hemoglobin (HbA1c) level goal established, minimizing glycaemia variability, and helping predicting the risk of severe hypoglycemia.(12)(13)(14)(15)(16)(17) When performed several times a day, SMBG provides an opportunity to correct glycaemia and improve the quality of glycemic control once the insulin regimen has been established, which has led to believe that its benefits are less clear in Non-Insulin-Treated patients.(15) In this sense, a meta-analysis conducted in 2012 showed that SMBG carried out regularly by Non-Insulin-Treated T2DM patients was associated with a statistically significant glycemic control positive result, but without clinical relevance, for it reported a 0.26% decrease in HbA1c levels (95%CI: (-0.39)-(-0.13)) in favor of SMBG after 6 months of implementation.(16) Likewise, in 2013, SMBG in this population was supported by the T2DM management guidelines of ALAD (17), particularly for the initiation or adjustment of medication in intercurrent situations that may decompensate glycemic control and in cases where a better understanding of the factors associated with oscillations in glycaemia is desired.(17) Also, the uncertainty on the role of SMBG in of non-insulin users with diabetes was addressed in 2014 by the ADA Association in a document on diabetes management guidelines where it is recommended to use this tool in a broader educational context and to help guiding treatment decisions in insulin and non-insulin users with T2DM.(13) In order to address SMBG role in non-insulin users it is necessary to review its importance in the different T2DM management strategies.
For SMBG to be an effective self-management tool in non-insulintreated patients with T2DM, both the patient and the physician must actively engage in performing SMBG, interpreting the results obtained and acting based on said values.Thus, the objective of the present study is to interpret and describe the results of the different studies that have addressed this issue in order to present a comprehensive account of the current evidence on SMBG in non-insulin-treated T2DM patients, and to present other clinical scenarios where SMBG is required.

Materials and Methods
A narrative literature review on SMBG in T2DM patients was conducted.Stages of the literature review were as follows: bibliographic search, selection of articles and review of the selected studies references.In addition, some of the articles included in the references of the selected publications were also added in the final selection upon meeting certain criteria (described in the following paragraphs).
During the first stage of the review, a search strategy was established taking into account the different T2DM management scenarios according to the 2017 management guidelines of ADA.(18) Then, the initial search was made from March 2017 to July 2017 under the following parameters: • Metasearch engines and digital databases: Pubmed, ScienceDirect, Embase, SciELO, Cochrane and Medline.• Search strategy: ("Self-Monitoring Blood Glucose" AND "Health Education" AND "Type 2 Diabetes Mellitus") OR ("Self-Monitoring Blood Glucose" AND "Lifestyle Changes" AND "Type 2 Diabetes Mellitus") OR ("Self-Monitoring Blood Glucose" AND "Diabetes Mellitus-Non Insulin Dependent" AND "Type 2 Diabetes Mellitus"), OR ("Self-Monitoring Blood Glucose" AND "Diabetes Mellitus -Insulin Dependent" AND "Type 2 Diabetes Mellitus") • Time frame: 2010-2017.
• Languages: English and Spanish.
• Type of studies: clinical practice guidelines, observational studies, controlled and randomized clinical trials, and systematic reviews or meta-analyses.• Eligibility criteria: use of evidence and graduation scales of the recommendations, and being published by authors affiliated to institutions recognized worldwide.
After the initial search was done, a total of 1062 documents were found.The title and abstract of the 1062 records were read individually, and based on the eligibility criteria described above, the following articles were excluded: those with redundant information in relation to articles already selected, those addressing topics unrelated to SMBG in T2DM.Afterwards, duplicate records were removed, and 26 articles were selected.
Finally, after an exhaustive manual review of the references included in this 26 articles was made, some articles found in said references and which met the inclusion criteria described before were added to the final selection of studies regardless of their publication year.Likewise, these articles included some review articles known to the authors and useful historical references about SMBF in T2DM provided their full text access availability and that they were consistent with the objective of the literature review.

Results
A total of 1 062 records were found after the initial search was performed.After reading the title and abstract of each article, based on the inclusion criteria abovementioned, and after duplicates removal was done, 1 036 were excluded, which resulted in the selection of 26 articles.In addition, 24 more articles found in the references of these 26 articles and published before the time frame were also included.In the end, 14 controlled clinical trials, 13 observational studies, 10 clinical practice guidelines, 7 narrative reviews, 5 meta-analyses, and 1 systematic review were included in this narrative review.The screening and selection process are shown in Figure 1, while Table 1 present the main characteristics of the studies included.Clinical effectiveness of SMBG in improving glycemic control is limited in people with T2DM who are on an oral agents treatment or with a diet alone management approach, and therefore it is unlikely to be cost-effective.SMBG may only lead to a better glycemic control in the context of appropriate education interventions, both for patients and health-care professionals, on how to respond to these data in terms of lifestyle and treatment adjustment.Likewise, SMBG might be more effective if patients are able to self-adjust their drug treatment.
SMBG in Non-Insulin-Treated patients, with or without instruction regarding the use of these findings to adjust self-care practices, did not lead to a significant improvement in glycemic control compared to usual care monitoring through glycosylated hemoglobin levels.There was no convincing evidence supporting the recommendation for routine self-monitoring in all patients, nor evidence of improved glycemic control in predefined patient subgroups.Observational study

Insulin-Treated T2DM patients
Intensive insulin therapy in insulin-treated diabetes patients effectively delays the onset of diabetic retinopathy, nephropathy, and neuropathy and slows downs their progression.

Malanda et al. (16) 2012 Netherlands Meta-analysis Non-Insulin-Treated T2DM patients
After six months of implementing SMBG in Non-Insulin-Treated T2DM patients, its effect is small and it subsided after 12 months of implementation.It did not have an impact on patients' satisfaction, their general well-being or their health-related quality of life in general.
Pan In patients using insulin SMBG is needed for self-management and for the adjustment of the dose.In the case of patients who are administered oral medication, profiling glucose trends and high or low blood glucose confirmation can be a useful complement for successful management of the disease.Use of SMBG postprandial data to make therapy adjustments was associated with a significant regression of carotid intima-medial thickening, and with a reduction in glycosylated hemoglobin levels.

Discussion
Based on the literature review carried out here, it is possible to say that SMBG practice and how it is perceived depends on the different T2DM management scenarios.Moreover, it was also revealed that adherence to SMBG is affected by several factors including patients' education level, health professionals' education level on DM and SMBG, availability of medical insurance, treatment regimen, and the frequency the patient goes to the physician office for follow-up purposes.Also, there is evidence supporting that SMBG, together with a proper results interpretation, can empower patients and promote selfmanagement.Likewise, there are many studies reporting an association between SMBG frequency and the degree of glucose control in Non-Insulin-Treated T2DM patients.
Self-monitoring of blood glucose and patient education SMBG is the measurement of blood glucose by using a glucose electrochemical biosensor in a capillary blood sample obtained from the tip of a finger, then this information is recorded by the patient, either on a notebook or a computer, for follow-up purposes.Afterwards, these data are used by patients and health providers to determine the presence of hyperglycemia or hypoglycemia and to make decisions regarding the adjustment of insulin doses, the use of other medications, or modifications in the patient's lifestyle, including dietary and physical activity habits.(14,16,19) In order to ensure that the information provided by SMBG is accurate a series of steps are required, besides it is also necessary that the patient fully understands the blood glucose measurement process.Next are the main considerations to take into account in order to obtain an adequate blood glucose measurement (21): • Clean and completely dry the area where the sample is going to be taken from.Also, the electrochemical glucose biosensor, the test strips and the Quartz Crystal Microbalances must be handled with clean and dry hands.• Test strips are single use only for each electrochemical glucose biosensor, and must be kept in the original container at all times before use, since their component can be affected by moisture.Also, expiration date must always be checked.• The equipment and supplies necessary for making the measurement must be obtained beforehand: lancing devices may vary, but generally these are made up of a microlance needle that punctures the skin.Thin and sharp microlens are more comfortable, and must not be reused or cleaned.
• The settings of the lancing device must be adjusted in order to control the depth of the puncture, thus achieving a less painful experience and a better blood sample size.• Application of the microlance needle: press it against the already prepared area to puncture the skin.The puncture will be less painful if made on the sides of the fingers or at the level of the palm.Preferably use the third, fourth or fifth finger.• Obtaining the blood sample: the sample is obtained from the base of the finger to one end of the microlance needle.It is not recommended to press it directly.• Place the blood sample in the electrochemical glucose biosensor for its analysis and get the glycemic value.• Non-reusable supplies and the lancet device must be disposed properly according to local waste management regulations.• Link the glycemic value that was recorded locally (on a notebook or a computer) with the information already recorded and stored in the electronic platform with Internet Access.
Provided that there is a wide variety of electrochemical glucose biosensor devices available on the market, some features like specific functions, error messages, and date and time settings should be consulted in their respective user manuals.In some cases blood glucose measurement accuracy may be affected by the use of medications, room temperature factors, hematocrit levels, and the technique used to carry out the measurement.( 22) Electrochemical glucose biosensors with glycemic 20% error margin have been recommended for use in SMBG.Recognition of the biosensors margin error is important in the variability of its accuracy, for in many cases patients perform a second blood glucose measurement and they are concerned by the difference between both results.(23) In the management of diabetes, the patient's level of education on diabetes and the ability to understand the basic considerations required for SMBG must be considered.Likewise, goals setting by the health care provider is a useful strategy for obtaining results from SMBG.When results obtained before having breakfast are consistent with a high glycaemia, drugs acting on hepatic glucose production can be used.On the other hand, postprandial glucose levels (2 hours after eating) will help understanding the impact of food intake on glycaemia, and in some cases they might be used to suggest dietary modifications or using medications such as oral anti-diabetic medications or insulin.(21) Physical activity and dietary habits are to be considered when assessing appropriate adjustments in SMBG, and when developing a treatment strategy; also, the goals that have been set in order to achieve self-care behaviors should be taken into account.(24) SMBG specific schedule will vary in each patient depending on the progression of the treatment and the particular clinical context.
Short and intense periods of SMBG, before and after each meal, and before going to sleep at night allow identifying glycaemia patterns, as well as the existence of hyperglycemia, (before breakfast, preprandial or postprandial).(21)(22)(23)(24) Al-Keilani et al. (25), in a study conducted in Jordan, assessed the adherence of diabetic patients to SMBG, as well as its predictive factors, reporting that the frequency of SMBG implementation was related to the treatment regimen, since it was found that in those undergoing insulin therapy or using oral hypoglycemic agents SMBG implementation was more frequent than in other groups (p<0.001).Likewise, these researchers also reported that the frequency of said implementation was associated with the reasons why these patients were actually performing SMBG, stating that the highest values were observed in those who carried out SMBG to determine if they had hypoglycemia (48.9%) or hyperglycemia (48%), or to inform their treating physicians about this situation.(25) Due to its cost-effectiveness, SMBG could be recommended based on each patient's individual treatment for diabetes, but this is still under discussion.In this sense, a prospective study showed that the provision of the necessary supplies for SMBG implementation in noninsulin-treated T2DM patients was associated with a decrease in their HbA1c levels after 3 and 6 months of its application (1.8% and 1.7%, respectively).( 26) Furthermore, an adequate before breakfast glucose correlation with glucose levels measured by SMBG was found, and a decreased risk of coronary heart disease, within a 10 year period, compared to the control group was reported.(26) Alternatively, patients can use a staggered schedule and check their blood glucose levels several times a day during the whole week, for example a preprandial and 2-postprandial implementation strategy, since it will allow the patient to have feedback regarding food choices for a given meal.Some recommendations to take into account when teaching how to perform SMBG include (24): • Provide simple and specific instructions according to the patient's level of understanding.• Ensure that the patient proves he is able to follow the instructions to carry out SMBG. • Provide the patient with written recommendations on frequency, time of assessment and desired results.• Observe how the procedure is performed by the patient in the follow-up visits.• Inform the patient of problematic SMBG values and discuss possible solutions.• Acknowledge any achievement obtained through SMBG.
• Find out the relationship between SMBG and physical activity, diet, use of medications or stress • Give clear recommendations on how to proceed in case of blood sugar imbalance (hyperglycemia or hypoglycemia).
SMBG should be performed depending on the assessment of the disease, whether it is a preprandial or postprandial measurement, or at times where glycaemia might be potentially low.Those patients who turn to carbohydrate consumption to adjust insulin doses and postprandial glycaemia levels are required to set SMBG goals that may be more intensive than those for patients who maintain a good control by using oral medications.While therapeutic adjustments are in process, SMBG shall be frequent, but once the therapy has been finally established, its frequency and intensity can be modified based on the patient's schedule.(17,18) Once T2DM has been diagnosed, patients must enter a structured educational program, in which detailed information on the disease is provided to empower the, to achieve self-control.(18) It is recommended that these patients initially receive instructions on how to perform SMBG and routine follow-up in order to use appropriately the information obtained in the therapeutic adjustments; likewise, SMBG application technique should be evaluated at regular intervals, for the patient may lose the ability and competence provided by said empowerment.(18) Finally, concerning patient reeducation, there are few studies reporting the effectiveness of long-term educational interventions, but positive results have been described regarding glycemic control and anthropometric parameters in education programs lasting from 2 to 5 years.(27)(28)(29) Based on these findings, the implementation of reeducation interventions on SMBG every 2-5 years is suggested.(17) Self-monitoring of blood glucose in patients whose diabetes treatment is based on lifestyle changes As in any other intervention for treating any disease, patient's adherence is fundamental to achieve good results.The World Health Organization (WHO) defines adherence as the degree to which a person's behavior coincides with the recommendations given by a health professional (use of medications, adopting healthy eating or lifestyle habits).(30).
In patients recently diagnosed with T2DM further research is required to determine whether lifestyle changes will lead to going back to normoglycemia, since so far the observed long-term adherence is not homogeneous and results have not been conclusive.In this case, SMBG constitutes a tool encouraging patients to adapt their lifestyles more effectively in order to achieve a better glycemic control, which empowers them to play a more active role in controlling the disease.(31) In this regard, in a randomized, controlled clinical trial a comparison between SMBG and HbA1c in terms of the management of newly diagnosed T2DM patients was made, and it was reported that the implementation of SMBG was associated with a higher regression rate (HbA1c <6% only metformin) and remission rate (HbA1c 6%-6.4%)compared to the control group (39% vs. 5% [p<0.001], and 37% vs. 30% [p<0.001],respectively).(32) Also, a higher percentage of patients in the cases group who achieved a meta score on a pre-established lifestyle scale compared to those in the control study (38.4% vs. 9.7% respectively, p<0.001) was observed, as well as an inverse correlation between SMBG and HbA1c levels (p<0.04).(32) This means that the association of SMBG with lifestyle changes effectively improves metabolic control in people recently diagnosed with T2DM, improving their adherence to nutritional recommendations and increasing their level of satisfaction without increasing the risk of developing severe hypoglycemia.On the other hand, SMBG implementation also allows healthcare personnel identifying if therapeutic adjustments are needed when glycaemia levels in SMBG values are not as expected.(32) This suggests that programs based on SMBG should be extended to primary care contexts, where patients with diabetes are usually treated.(31,32) Self-monitoring of blood glucose in T2DM non-insulin pharmacological management Studies on SMBG in T2DM patients treated with a non-insulin pharmacological therapy are of contemporary emergence.(33)(34)(35)(36)(37) Currently, the ADA states that SMBG can be a useful tool in making decisions on treatment or self-care in non-insulin users.(18) On the contrary, in its diabetes management guidelines, the International Diabetes Federation (IDF) says that there is still limited evidence regarding SMBG regimens in T2DM insulin-free management, but that it does not have to be performed daily.(38) In this regard, Polonsky et al. (20), in a controlled clinical trial, found that after 12 months of implementing structured SMBG in patients with a poor metabolic control, a significant reduction of HbA1c levels was observed (1.2%, p=0.04), which was associated with an improved glycemic control, thus making possible to make therapeutic changes in a timely and aggressive manner in Non-Insulin-Treated T2DM patients, without diminishing their general well-being.(20) Malanda et al., in a systematic review and meta-analysis that summarizes clinical trials evidence on the effects of SMBG since 1989, reported that the effect of SMBG after 6 months of implementation in non-insulin users whose T2DM diagnosis was ≥1 year was low, with a 0.26% HbA1c level reduction (95%CI: (-0.39)-(-0.13)),and that after 12 months, said effect was even smaller and not statistically significant (0.13% [95%CI: (-0.31)-(0.04)]);also, evidence supporting that SMBG had an impact on the patient's satisfaction, well-being or quality of life was not found.(16) In 2017, Young et al. (39), in a controlled and randomized clinical trial conducted in patients with non-insulin-dependent T2DM, compared three average blood glucose (AG) approaches in terms of HbA1c effects and improvement of quality of life indexes , namely: absence of SMBG, SMBG once a day, and SMBG application once a day with improved feedback for the patient, yet no significant differences regarding HbA1c reduction were observed in the three groups (p=0.74), with an estimated average HbA1c reduction of 0.09% in the group where SMBG with improved feedback was implemented (95%CI: (-0.32)-(0.14%)) vs. a 0.05% reduction in the non-using SMBG group (95%CI: (-0.27%)-(0.17%)).( 39) Likewise, no significant differences were found regarding quality of life indexes and key adverse events such as hypoglycemia frequency, health resources use or insulin initiation.(39) In addition, Farmer et al. (40), in a meta-analysis with 2 552 subjects from 6 clinical trials, reported that after 6 months of SMBG implementation in non-insulin-treated T2DM patients a 0.25% HbA1c reduction (-2.7mmol / mol [95%CI: (-3.9)-(-1.6)]) was observed in comparison with those who did engage in SMBG.Furthermore, other clinical trials have shown greater reductions in HbA1c levels by associating SMBG with therapeutic, educational or behavioral interventions aiming to achieve better glycemic control practices.(41,42) Regarding its frequency, no differences were found regarding glycemic control when SMBG was used with a greater intensity, and it is suggested that both the frequency and intensity of self-monitoring should be related to the progression of the disease and the complexity of the treatment.(43,44) Given the importance SMBG represents for non-insulin users, it is necessary to determine its frequency and intensity based on the management of the disease at the time of its implementation.(40)(41)(42)(43) Self-monitoring of blood glucose in in insulin-treated type 2 diabetes mellitus Currently, SMBG is considered an essential component in the management of insulin-treated T2DM patients and its use is mandatory.(17,18) In this regard, Schnell et al. (45) found that use of SMBG in these patients increased by 23% between 1993 and 2009.Also, there are many prospective and observational studies addressing the use of SMBG in insulin-treated T2DM patients.(7,46,47) For example, two controlled and randomized studies described the importance of SMBG in this type of patients when it was associated with a structured plan to treat elevations in their glucose levels.(48,49) Another example can be found in the study conducted by Ohkubo et al. (7), where it was reported that intensive insulin therapy guided by SMBG might reduce the risk of developing micro-vascular complications in T2DM in comparison with conventional therapies.On the other hand, Murata et al. (47) in a study where an intensive SMBG implementation was performed for 8 weeks in a metabolically stable insulin-dependent population group of veterans with T2DM, reported a 0.3% HbA1c reduction approximately one year after the implementation.Somehow, it should be noted that these positive results were only possible if the patient's adherence to the established SMBG regimen was ≥75% or if the HbA1c baseline was ≥8% (64 mmol/mol).(47) Regarding the frequency of application, it has been recommended that SMBG should be performed before having meals or snacks, and occasionally after eating (postprandial measurement), and before going to bed or exercising when hypoglycemia is suspected and after it has been treated, and before engaging in activities such as driving a vehicle.(18) Although every individual has different needs, SMBG intensity, schedules and frequency must be determined based on the complexity of the insulin schemes, and the measurement may be required from 6 to 8 times per day.(17,18,38,50) Finally, it is worth noting that improving HbA1c levels is not the main purpose of using SMBG in insulin-treated T2DM patients, but decreasing the risk of developing severe hypoglycemia, as well as providing the patient the necessary knowledge, through educational interventions, to solve hypoglycemia instances happening at home.(17,18,(47)(48)(49)(50).

Self-monitoring of blood glucose in daily life
The implementation of SMBG as a habit in daily life represents an important step forward in the management of diabetes, since it offers benefits such as optimizing the treatment of complications, encouraging patients to participate in the control and treatment of the disease, and allowing them to develop self-confidence.(19).In the clinical practice, deciding whether patients need SMBG or not, as well as its frequency, will depend on aspects such as the type of therapy they were prescribed for treating the condition, the need to titrate the insulin dose or change the insulin regimen, and their individual preferences, skills and visual acuity.It is also important to note that SMBG frequency may also depend on financial considerations and health care systems coverage.(20) As far as T2DM can be prevented, it is important to continue with an effective medical management, as its prevalence is increasing rapidly.(1-5) Self-management of diabetes involves effective patient education as an evidence-based component of treatment and care that aims to achieve optimal metabolic control, better compliance with medical treatments, prevention of complications, and a better quality of life.(11)(12)(13) The lack of clear and easy-to-follow guidelines is a major obstacle hindering the effective use of SMBG.Somehow, developing a coherent set of recommendations is especially challenging due to the disparities in resource availability among health care systems, variations in diabetes management practices, and diverse sociocultural settings.(20)(21)(22) The goal of using SMBG is to obtain detailed information of the glycemic profile at different times in order to provide feedback in the context of self-care and an established pharmacotherapy.Therefore, it can facilitate making lifestyle changes and therapeutic adjustments, as well as empowering patients and improving their adherence to treatment.(16,(19)(20)(21) The role of patient education in self-care is to make patients aware of their condition and the importance of controlling the disease, since this will help improving their health condition and their quality of life.(22)(23)(24) Ideally, anyone with diabetes should use SMBG to achieve good glycemic control and thus avoiding or delaying the onset of chronic complications.(31,32) Both the physician and the patient must have the necessary knowledge and be encouraged to evaluate blood glucose levels frequently.This way, better decisions regarding the management of the disease will be made.(14,16,(19)(20)(21) The frequency and schedules for performing capillary blood glucose tests should be individualized based on the objectives to accomplish in each patient, the type of drug that has been prescribed for use, the degree of control, the risk of developing hypoglycemia, and the need for short-term control.(17)(18)(19) In the case of Non-Insulin-Treated diabetes patients, usually the disease has a few years of evolution or an adequate pancreatic reserve of insulin is maintained, which allows a favorable response when dose adjustments are made or when a second or third medication is added.In addition, several studies have found an association between the frequency of SMBG use and an improved glycemic control in this therapeutic context.(20,(34)(35)(36)(37)(39)(40)(41)(42)(43).
The expectation caused by using SMBG in a non-insulin dependent patient will depend on the evolution of the disease.Therefore, the health provider must always give the patient clear information on the objectives of glycemic control.(33)(34)(35)(36)(37)(38).Also, while it is a fact that there are several factors influencing glycemic control, by implementing SMBG in a structured way HbA1c levels can be reduced by 1.2% under the best circumstances.(20) In the particular case of patients using insulin, it is assumed that there is a greater commitment of their pancreatic reserve, which in turn requires its replacement with insulin.Therefore, they must be given recommendations in terms of eating and physical activity habits so that they don't constitute a negative element in the control of the disease.Likewise, in order to achieve the established control goals, patients are required to monitor their glucose on a daily basis.(7,17,18,46,47) Ideally, capillary blood glucose should be measured before each of the three main daily meals and 2 hours after each measurement is made, so that there are enough data to assess the fasting glycaemia as postprandial excursions and make the relevant insulin dosage adjustments.(17,18,38,50) It is widely known that self-monitoring will help achieving good glycemic control, however strict control may also increase the risk of developing hypoglycemia.(47)(48)(49)(50) Finally, the following recommendations on SMB in T2DM are proposed (table 2): Source: Own elaboration.
Although the long-term influence of SMBG in T2DM is supported by several studies (6,8,(14)(15)(16)(19)(20)(21), an association between anxiety or depression and SMBG application has been described in some cases ( 9), yet it is worth noting that said mental conditions may have already existed before SMBG implementation or comprise a base comorbidity, and might not be directly caused by SMBG itself.

Conclusions
SMBG effects will be positive as long as both the patient and the health professional are well informed about it, which is only achievable through appropriate educational interventions.In the case of health professionals, they must be provided with sufficient knowledge on SMBG application frequency and schedules, while in the case of patients, they must be instructed on SMBG application techniques and what the objectives of this tool are, which in turn will make them have expectations in relation to the prognosis of the disease.
Although the results reported in several studies on SMBG in Non-Insulin-Treated T2DM patients vary, and its use is still under debate, it is possible to say that SMBG is a tool that has been reported to have a great impact on glycemic control and in decision-making processes regarding timely and appropriate therapeutic changes to be made.
It is important to bear in mind that the individual approach of the patient is a key requirement to obtain positive results after its implementation.Furthermore, SMBG frequency, intensity and schedules will depend on the progression of the disease.Finally, in spite of the advances reported by the current evidence regarding the association between SMBG and T2DM management, further research is required to confirm said association.

Figure 1 .
Figure 1.Flow diagram depicting the selection process of the articles included in the review.Source: Own elaboration.

Table 1 .
Characteristics of the studies included in the review.Part A.

Table 1 .
Characteristics of the studies included in the review.Part A (Continued).
Education interventions aimed at the patient and prescription audit may optimize the use of SMBG, as well as the outcomes of the treatment.

Table 1 .
Characteristics of the studies included in the review.Part A (Continued). in all types of treatment approaches for diabetes management in order to achieve near normal glucose control without increasing the risk of developing hypoglycemia.The recommended frequency and pattern of SMBG depends on the type of diabetes, the treatment approach and the glycosylated hemoglobin and pre-and postprandial blood glucose levels that have been individually established.After one year if implementing SMBG there is not clinically or statistically significant differences in terms of glycemic control between those who used SMBG and those who did not.
SMBG is important for self-management, since it improves glycemic control.There is a need to educate healthcare payers and providers and patients in order achieve better access to and affordability of self-management tools and patient education strategies.

Table 1 .
Characteristics of the studies included in the review.Part A (Continued).Intensified blood glucose monitoring improved glycemic control in a large cohort of stable, insulintreated veterans with T2DM.SMBG provided a strong stimulus to improved self-care, which resulted into clinically important and sustained reductions in glycosylated hemoglobin levels.

Table 2 .
Self-monitoring recommendations in type 2 diabetes mellitus.