Database searches yielded 2701 records. Of these, 366 duplicates were excluded. Title and abstract screening excluded 2247 records. Of the remaining 88 records, 49 were excluded during full-text screening. Citation searches identified 1528 additional records, of which 142 were duplicates. A single study among the remaining 1386 records was included after screening. Thus, 40 reports from 39 studies were included in the review (Figure 1). Interrater reliability (IRR) was 83% for pilot screening and 92% for screening all records.
Characteristics of studies
Overall, 39 studies published between 1990 and 2022 were included. More than two-thirds of included reports were published in or after 2013 (see Supplementary Figure S1). Eighteen studies were conducted in North America, 17 in Europe (including Turkey and Israel), and four in Oceania (see Supplementary Table S3 for study characteristics).
Twenty-nine included studies had descriptive quantitative designs, with data collected through questionnaires. Five studies had qualitative designs, with data collected by individual interviews. Five study designs were mixed methods, using descriptive questionnaires based on focus group responses and observations (see Supplementary Table S3).
Quantitative study response rates were 3.6%–91%. A total of 11 340 GPs participated in quantitative studies, including the questionnaire phase of the five mixed-methods studies. Qualitative studies (including the focus group phase of the mixed-methods studies) had a collective total of 133 participants.
None of the included studies provided all the information sought on participants (that is, gender, age, years of experience, number of PWT2D seen, and level of interest in diabetes). However, participants tended to be predominantly male, with a mean experience of >20 years (see Supplementary Table S3).
Eight studies adopted a broad study focus (see Supplementary Table S4), in which GPs were openly asked what information they needed. The remaining studies used various forms of testing researcher-defined knowledge gaps.
Information needs synthesis
Findings about information needs are organised into eight main categories:
Medication
Eighteen reports described the need for information on type 2 diabetes medications. Five addressed appropriate prescribing behaviour, pertaining to GPs’ ability to choose appropriate medications. Two studies by the same author found that GPs do not fully understand differences between glucagon-like peptide-1 (GLP-1) receptor agonists and dipeptidyl peptidase-4 inhibitors, including mechanisms of action and clinical indications.28,29 One study found that half of GPs could not correctly identify contraindications for metformin.30 Another found that GPs chose GLP-1 receptor agonists even when insulin was more appropriate.31 The fifth study found suboptimal use of angiotensin-converting enzyme (ACE) inhibitors and angiotensin II-receptor blockers, compared with sodium-glucose transport protein 2 (SGLT-2) inhibitors, in the treatment of comorbid chronic kidney disease (CKD) and type 2 diabetes.32
Four reports addressed non-specific pharmacological management of diabetes. Two included studies found that GPs wanted more education on oral diabetes medications.33,34 One study surveying GPs on knowledge about oral medications found that they most often correctly answered questions about metformin and sulfonylurea.35 One study identified a learning need among GPs on the use of injectable therapies.36
Twelve included studies addressed information needs related to insulin. Four studies reported findings related to initiating insulin treatment: one identified inadequate clinical experience as a barrier to insulin initiation,37 one reported on needed practical skills in injectable use,31 and two found that insufficient knowledge about insulin therapy was a barrier to initiation.38,39 One study found a specific lack of knowledge about needle sizes in injection devices.40 Two studies found that GPs requested education on adjusting and managing insulin treatment.33,36 Another two studies by the same author found a knowledge gap in navigating different insulin regimens,28,29 and three studies found a need for general knowledge about insulin characteristics.34,35,41
Nine studies addressed specific drug types. Two reported suboptimal use and knowledge of SGLT-2 inhibitors.32,42 In one study, GPs thought they knew enough about GLP-1 receptor agonists,42 but another study found that they were generally insufficiently aware of the effects of GLP-1 receptor agonists.43 De Lusignan et al also found that GPs prescribed GLP-1 receptor agonists when insulin was more appropriate.31 One study found that almost all responders knew the benefits of ACE inhibitors in delaying progression of diabetic nephropathy.44 One study found that GPs lacked knowledge on thiazolidinediones and their possible cardiovascular consequences45 to a significant degree.
Management
This category included all studies on management and treatment of type 2 diabetes that were unrelated to pharmacological treatment or management of complications. Nine reports contained findings related to managing type 2 diabetes. Four reported a lack of knowledge about hypoglycaemia, with Fisher et al46 directly linking insufficient knowledge to suboptimal treatment decisions.33,39,46,47 Fogelman et al43 and Phillips and Dromgoole34 found that 60% of GPs reported a lack of knowledge on nutritional issues and 68% reported an interest in more training.
Two studies found a need for knowledge about hypertension, and Rubin et al found that only 31% of GPs knew the blood pressure goal for PWT2D.33,41 Two studies found that GPs lacked knowledge about managing diabetes through fasting practices during Ramadan.48,49
Marsden and Grant analysed a broad range of topics that GPs requested education about.33 In addition to identifying knowledge gaps related to hypoglycaemia and hypertension, they found that managing weight problems (49% of GPs) and managing PWT2D at home (45% of GPs) were among the most common information needs related to type 2 diabetes.33
Complications
The complications category was the largest. Five articles reported a need for knowledge about managing complications. Phillips and Dromgoole reported that as many as 100% of GPs wanted education on vascular complications and 81% wanted information on acute complications.34 Cytryn et al38 and Thepwongsa et al36 found that they lacked confidence in managing comorbidities and complications. Shubrook et al reported that lack of knowledge of cardiovascular outcome trials had implications for care of PWT2D and cardiovascular disease.50 One study found that GPs overestimated the impact of strict metabolic control on macrovascular complications and overall mortality.47
Chu et al32 and Lo et al51 identified a need for education on prevention, earlier diagnosis, and early intervention for CKD. Lo et al also found that 73% of GPs were uncertain about the definition of CKD, and 80% wanted more information on managing patients with comorbid diabetes and CKD.51 One study found that GPs were unsure and sometimes factually incorrect when responding to questions about metformin use in patients with CKD.30
Two studies found that GPs expressed a need for education on eye complications of diabetes and specifically on retinal examination,33,52 with Delorme et al reporting GPs’ lack of confidence in their ability to screen for diabetic retinopathy.52 One study noted that GPs were well educated about diabetic eye disease.53
Chu et al32 and Wong et al44 reported that GPs used urine albumin-to-creatine ratio (uACR) screening insufficiently, and 39% chose inappropriate methods for detecting microalbuminuria. Two studies found that GPs lacked knowledge about the relationship between diabetes and periodontal diseases,54,55 as well as a general knowledge and training gap related to oral health.55
Just 2% of GPs requested training on diabetic foot complications34 but a different study found that they were dissatisfied with the accessibility and availability of diabetic foot ulcer guidelines.56
One study assessed knowledge of risk factors for CKD, reporting that most GPs correctly identified hypertension and diabetes mellitus as risk factors.57 Three studies investigated knowledge about specific complications, that is, Charcot neuroarthropathy, limited joint mobility (LJM), and non-alcoholic fatty liver disease (NAFLD). Bilello and Jupiter found inconsistent knowledge about managing Charcot neuroarthropathy among internal medicine physicians and GPs,58 and Alabdali et al found that most GPs who were asked were unaware that LJM was a diabetes complication.59 Lastly, Gracen et al found a gap in clinical practice related to the implementation of clear, evidence-based guidelines for NAFLD.60
Diagnosis
Three studies described the need for information on diagnosing type 2 diabetes. These focused on inadequate information about diagnostic criteria and cut-off points for tests such as fasting plasma glucose.35,38,41 Rubin et al41 found that only 49% of GPs knew the test criteria and Shahla et al35 found that they often incorrectly answered questions about the test criteria in the absence of type 2 diabetes symptoms.
Risk factors
Three studies analysed the need for knowledge about risk factors for diabetes. One asked GPs broadly about training needs, with 68% of responders indicating that they needed general knowledge about risk factors for type 2 diabetes.34 One study reported that GPs needed more training about obesity because they were not sufficiently informed on the risks and benefits of treatment, even though obesity is a well-known risk factor for type 2 diabetes.61 Rayanagoudar et al found a lack of knowledge among GPs about the long-term consequences of gestational diabetes, including the elevated risk of getting type 2 diabetes.62
Screening for diabetes
One report pertained to screening for type 2 diabetes. Whitford et al described the absence of knowledge on evidence related to screening for type 2 diabetes.63
Reasons for referral
Seven reports provided findings about information needs related to referring PWT2D to specialists. Three studies analysed the need for information on appropriate referral to a nephrologist,32,44,51 finding a need for more information and training on interpreting test results that should trigger referral, and on referral guidelines and pathways.
Two studies focused on type 2 diabetes and obesity, and potential reasons to refer patients for bariatric surgery.61,64 El-Beheiry et al found that nearly half of GPs did not feel adequately prepared to discuss the role of bariatric surgery and 75% did not follow referral criteria.64
One study evaluated information needs related to Charcot neuroarthropathy, concluding that lack of familiarity with symptoms may lead to fewer referrals than appropriate.58 The referral rate among GPs was 41.7%.
Finally, one study tested the tendency of GPs to refer patients to either endocrinologists or certified diabetes educators (CDE) under varying care circumstances.28 GPs were most likely to refer patients who were considering insulin pump therapy (>80%) or had experienced multiple hypoglycaemic events (50%). The most frequent reason for referring patients to CDEs was complex dietary issues.
Knowledge of guidelines
Eleven studies broadly indicated that GPs often lacked knowledge of appropriate guidelines, in terms of both familiarity with the most up-to-date guidelines and following guideline recommendations. Four studies found a general need for more information and training on applying type 2 diabetes guidelines.10,28,65,66 Williamson et al described GPs as less familiar with current guidelines, whereas Rätsep et al found inappropriate management of glycosylated haemoglobin and weight reduction when inquiring about guideline-recommended follow-up.28,66 Additionally, the use of appropriate medications was an issue.
Six reports provided findings about GPs’ limited knowledge of guidelines when treating type 2 diabetes and coexisting complications.30,32,44,52,60,61 Three studies on CKD, one on retinopathy, one on NAFLD, and one on obesity and bariatric surgery all found a lack of knowledge about the most appropriate guidelines for screening and managing comorbidities.
When asked about their preferences, 20% of GPs reported wanting more training on the organisation of diabetes care,34 an information need most often addressed by guidelines.
See Supplementary Table S4 for a full overview of information needs.
