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People with type 2 diabetes often take many medications – a significant proportion of patients take more than eight. There will always be a tension between multiple drug therapy to achieve recommended goals on the one hand and health issues from polypharmacy, drug–drug interactions and confusion (especially in the elderly) on the other. Refer to the Australian Institute of Health and Welfare (AIHW) for more information.
In 2007–08, 63% of people with diabetes reported using medications to help manage their condition; 13% of people with type 2 diabetes reported using insulin; and approximately 6% of people with diabetes reported using vitamin or mineral supplements or herbal remedies, although this is likely to be underestimated.214
Additionally, approximately 50% of patients do not take their medication doses exactly as prescribed by their healthcare professional.215 This may be a barrier to achieving treatment targets and result in adverse outcomes.
It is important to understand the overall medication burden as it can lead to many issues including non-adherence, increased risk of falls and hypoglycaemia.
Contributing factors to non-adherence may include cost, complex treatment schedules and side effects.
GPs should be aware and assess for non-adherence, possible drug interactions and side effects in every patient with type 2 diabetes. Patients on prescribed monotherapy may be using complementary therapy or misusing their prescribed medication.
Medication use, both conventional and complementary, should be reviewed at least once per year as part of the annual cycle of care.216,217
The RACGP’s Putting prevention into practice: Guidelines for the implementation of prevention in the general practice setting218 provides some strategies to address patient adherence on pages 24–26.
For information regarding drug interactions, consult publications such as the Australian medicines handbook.
Pharmacists can be an invaluable resource as they have access to extensive medications databases, can detect potential drug interactions, and provide useful advice to the health professional and person with diabetes.219,220
Important drug interactions and side effects
People with diabetes may be taking multiple glucose-lowering medications in addition to other prescription and non-prescription agents. Some drug interactions are dangerous and special care is required in older patients and patients with comorbidities such as renal impairment and autonomic neuropathy. A full list of potential drug interactions is beyond the scope of these guidelines. Use a home medicines review and pharmacy support on an individualised basis in any patient with diabetes.
Reporting of adverse events
Many medications are becoming available for the management of diabetes for which long-term safety data is not yet available. Primary healthcare professionals have an important role to play in identifying and reporting adverse events and possible drug interactions. These should be reported to the TGA, either online or by completing the Blue card.
Home medicines review
Multiple systematic reviews have concluded that there is a lack of evidence for improved health outcomes for medication reviews. Benefit has been proposed where pharmacists work in close liaison with primary care doctors.221 The review should include consideration of:
- the need for each medication
- issues around patient compliance and understanding of the medication
- enquiry regarding medication side effects, particularly falls and cognitive impairment
- the use of aids such as dosette boxes and Webster packaging.222
The use of complementary medicines is increasing in Australia. A survey of pharmacy customers found that 72% of respondents had used complementary medicines within the previous 12 months; 61% used prescription medicines daily and 43% had used these concurrently. Multivitamins, fish oils, vitamin C, glucosamine and probiotics were the five most popular complementary medicines.223
A substudy of the Fremantle Diabetes Study found that 23% of participants had consumed at least one complementary medication in the last year. Of the medications used, approximately 42% potentially necessitated additional patient monitoring or could be considered inappropriate for patients with diabetes.216
Predictable positive and negative interactions between complementary medicines and prescribed diabetes medications may be variable as there is little formal assessment of many of these products.
NPS MedicineWise has compiled a guide to medicines information resources relevant to Australian health professionals.
Interactions can be checked by searching these resources, although NPS does not guarantee their completeness or accuracy.