This study indicates that while PCPs share some beliefs about initiating insulin, there is a lack of consensus about other aspects of insulin therapy. Most shared beliefs fall into one of four categories: benefits of insulin therapy vs. risks, positive experiences of patients on insulin, fears or concerns of patients still on oral therapy, and the management of and training for insulin use.
The majority of PCPs agreed that the benefits of using insulin to prevent or delay complications outweighed the risks of hypoglycaemia and weight gain for most patients. However, there was less consensus when the patient was severely obese or elderly. For example, while the clear majority of PCPs agreed that the benefits of insulin outweighed the risks of hypoglycaemia for most patients, 44% agreed that the risk of hypoglycaemia made them reluctant to prescribe insulin to most patients who were ≥ 85 years old. The risk of hypoglycaemia is greater in elderly patients who have poor or erratic nutritional intake and/or comorbidities (12
) and impaired recovery from hypoglycaemia (13
). However, there is no evidence to suggest that the treatment goal for otherwise healthy elderly patients should differ from that for younger patients (HbA1c ≤ 7%), and the PCPs in this study agreed.
Most PCPs agreed that patients feel much better after they have begun insulin and that patients can manage the demands of insulin. Several studies have confirmed that patients, including elderly patients, experience reduction in fatigue and increased feelings of well-being when they begin insulin and that these improvements are sustained over time (15
). Most PCPs also agreed that patients on insulin were satisfied with their insulin therapy. Studies show that patients on insulin, regardless of delivery mode (vial and syringe, pen or inhalation), have high levels of treatment satisfaction (19
In a review of medication–adherence literature for patients with type 2 diabetes, Rubin (22
) concluded that the adherence rate for oral antihyperglycaemic medication was approximately 65–85%, and insulin adherence may be slightly lower. In this study, nearly two-thirds of PCPs believed that their insulin-using patients were adherent, and only about a quarter of PCPs agreed that their patients on oral therapy would be less adherent to insulin therapy. Because the potential benefit patients receive from a treatment can be largely dependent on their adherence (22
), further research is needed to determine whether PCP perceptions of patient adherence to insulin are accurate. Most PCPs agreed that patients on oral therapy are afraid of insulin injections and that this fear is a barrier to initiating insulin. PCPs were also largely in agreement that patients on oral therapy would be reluctant to initiate insulin and would have feelings of personal failure. These general patient concerns are well documented in the literature (3
). Nearly all PCPs agreed that for most patients, education is the key to insulin initiation. However, Brunton et al. (23
) pointed out that this education is usually given when diabetes has progressed to the point that insulin is the only alternative for glucose control. They further stressed the importance of educating the patient at diagnosis about the disease progression of diabetes and the inevitability of needing insulin to maintain good glycaemic control, rather than using insulin as a threat to motivate patients.
Although Riddle (6
) identified the complexity of training patients in the proper use of insulin as a contributing factor to its under-use, more than half of the PCPs disagreed that training was too complicated for patients or that follow-up was too resource-intensive for their staff. However, there was no consensus that the time needed for training in the proper administration and usage of insulin was too much for their staff. This is not surprising as educational resources available to PCPs for insulin initiation vary widely.
Primary care physicians also clearly lacked consensus on whether patients on insulin performed self-monitoring of blood glucose (SMBG) sufficiently for appropriate insulin use. Appropriate SMBG frequency varies according to insulin regimen: three or four times daily is recommended for multiple injections, less frequent monitoring is needed for less intensive therapy (24
). However, SMBG in patients with type 2 diabetes is often suboptimal (25
). Reimbursement and resources for SMBG instruction may be highly variable, and SMBG adds to the patient's ‘hassle factor’. These issues may contribute to lack of PCP consensus about patient SMBG sufficiency, but patient fear of SMBG probably does not influence this PCP belief (26
Primary care physicians exhibited a clear dichotomy concerning whether adherence to a diabetes regimen or following physician's recommendations would prevent patients with type 2 diabetes from requiring insulin. Disagreement with the first belief and agreement with the second raise the question of whether these PCPs respondents truly understood the progressive nature of diabetes. Because of the continuing decline in insulin secretion, within 6–10 years after diagnosis (sooner if the patient had type 2 diabetes for years prior to diagnosis) as many as 40–60% of patients with type 2 diabetes will need insulin to maintain glycaemic control (27
), regardless of adherence to medication regimens and/or following physician recommendations.
The three items with unimodal response distribution were based on Riddle's (6
) observations that many physicians worry that insulin therapy results in negative metabolic effects. The results of the United Kingdom Prospective Diabetes Study (29
) and the Diabetes, Insulin-Glucose, And Myocardial Infarction (30
) studies led Riddle to conclude that there is ‘compelling evidence’ that insulin treatment is not harmful with respect to cardiovascular disease and is most likely beneficial. A more recent retrospective observational study using a national health-claims database (31
) reported the probability of a cardiovascular event to be 34% less for patients with type 2 diabetes on insulin than for those not on insulin. PCP beliefs about negative metabolic effects of insulin may be based on lack of knowledge and indicate a need for continuing medical education.
Two-thirds of the PCPs in this study agreed with the statement ‘…the initiation of insulin is one of the most difficult aspects of managing my patients with type 2 diabetes’. When associations between PCP characteristics and beliefs were examined, very little difference was seen in beliefs by gender or type of board certification. However, PCP attitudes varied by both years of practice and average number of patients with type 2 diabetes seen per week. PCPs with more years of practice had more positive attitudes about patients on insulin than PCPs with less experience, perhaps simply because of more long-term experience with such patients. PCPs with the least practice experience disagreed more strongly than more experienced PCPs that insulin has negative metabolic effects. The beliefs of the least experienced may reflect the fact that the ‘compelling evidence’ mentioned by Riddle (6
) has been incorporated into medical student and resident education.
Primary care physicians who treated greater numbers of patients with type 2 diabetes per week appeared to be more risk-averse concerning insulin initiation compared with those who saw fewer patients, indicating that the diabetes care of many patients with type 2 diabetes is being managed by PCPs who have beliefs that suggest a reluctance to initiate insulin therapy in such patients.
A limitation of this study is that the data were self-reported and may differ from actual practice patterns of the study participants. However, other work has shown that physician attitudes are closely linked to behaviour (32
), leading us to assume that many PCPs delay the prescribing of insulin to patients with type 2 diabetes. Another limitation is that, according to the AMA master file of 2000 (33
), the percentage of female physicians in primary care (defined by AMA as general and family practice, internal medicine, obstetrics/gynaecology and paediatrics) in 2000 was approximately 34%. In our study, the percentage of female PCPs was 20%. Therefore, the attitudes of female PCPs may not have been sufficiently represented. Finally, another limitation is the survey administration: This study is generalisable to only those PCPs who have internet access and who would volunteer for such a study. Nevertheless, sampling was designed to ensure representation from all parts of the country and equal representation of family practitioners and internists.