Exercise-induced hypoglycaemia is a real consideration with insulin and/or insulin secretagogues such as sulfonylureas and glinides which increase insulin secretion, and dose adjustment may be necessary. The hypoglycaemic effects of sulfonylureas may also be enhanced with exercise. There is generally less concern about modifying the dose of other diabetes medicines for exercise.15

For people with diabetes who might be inspired to try their own low-calorie diet, Diabetes UK sets out advice. In addition to side effects such as constipation, dizziness and headaches, it warns people using insulin or sulphonylureas that being on a low-calorie diet can make hypos more likely. Note that the DiRECT trial excluded patients on insulin.18,24

As such, patients are advised to check with their GP first around safety, to discuss nutritional requirements, and also to be aware of what effect an LCD may have on any other conditions that are present. The patient will also need to be aware of whether medication changes may be necessary or whether to increase blood sugar testing frequency.18

When considering the impact of dieting on diabetes medicines, a Canadian review has noted that people with T2D following a VLCD (<800kCal/day) usually require medication to cease to prevent hypoglycaemia. However, for those who are fasting on just a couple of days a week (eg, the 5:2 intermittent energy restriction diet), medication may need to be reduced but not necessarily stopped.25

People on the 5:2 diet may therefore need to check blood sugar levels twice daily and report any cases of hypoglycaemia or hyperglycaemia so that medication may be adjusted accordingly, the study recommended.

More recently, a retrospective cohort study of T2D patients has looked at the effects of LCD weight loss with 900 kCal/day for 6-12 weeks with a professional dietary support programme for 12 months. After six months, participants had lost 16% of their weight. Drug doses had decreased or been discontinued as follows:26

·       sulfonureas 92.1%

·       insulins 86.5%

·       thiazolidinediones 78.8%

·       alpha-glucosidase inhibitors 77.8%

·       meglitinides 50%

·       dipeptidyl peptidase-4 (DPP-4) inhibitors 33.3%

·       metformin 32.8%.

At six months, 30% of patients were no longer taking diabetes medication, and had greater weight loss compared with those taking medication.

Diet and exercise therefore have the potential to make significant impact at all stages of the T2D continuum, with improved health outcomes and reduced healthcare costs. Healthcare professional input is important, so is it time to step up the action on diabetes?