Dr Katharine Morrison is a GP of 31 years in Ayrshire, West Scotland. She discovered the applications of low carb diets around 15 years ago when she tried the Atkins diet and noticed a significant improvement in her own health. She has since had success using low carb regimes with her type 2 diabetic patients and this allowed her to make choices around her own son’s diet when he was diagnosed with type 1 diabetes. Dr Morrison runs a diabetes education website, has co-authored papers on the use of low carb in metabolic syndrome and diabetes and has also written a diabetes diet book. This talk was given at the Public Health Collaboration conference 2018 at the Royal College of General Practitioners in London.
It is well characterised that tighter blood sugar control reduces complications in diabetes. Because of this, health authorities around the world recommend good control, although definitions of ‘good’ do vary; NICE define under 6.5% as good control. Even though there is debate around what a good HbA1c level is, Dr Morrison explains that we are currently nowhere near achieving even modest control. For example, DAFNE (considered the gold standard of diabetes education) graduates only improve their HbA1c from 79 to 68 mmol/mol (9.4% to 8.4%) on average and only 15% of pregnant women achieve an HbA1c of under 42 mmol/mol (6%) in the first trimester (higher HbA1cs are associated with foetal abnormalities). There are more statistics on top of these that indicate, on average, we are not doing so well when it comes to blood sugar control.
In contrast though, Dr Morrison explains that much better blood sugar control is achievable with a low carb diet. For example, by following Dr Richard Bernstein’s ketogenic diet including 6-12g of carbohydrate per meal, both type 1 and type 2 patients alike can achieve ‘normal’ HbA1c values outside of the diabetic and even prediabetic ranges (26-37 mmol/mol or 4.5-5.5%).
Once blood sugars have stabilised, low carb approaches also reduce the risk of hypoglycaemia. The mechanism for this is known as Dr Bernstein’s ‘rule of small numbers’. People with diabetes will experience blood sugar fluctuations as food is eaten and insulin is take, causing blood sugars to rise and fall, respectively. However, relative errors are made in the calculation of the amount of carbs eaten and so the amount of insulin needed to match it. There is also around a 30% variability in how much insulin is absorbed under the skin. If a large amount of carbohydrate is eaten, a large amount of insulin is required to deal with it and so, the larger the potential for error. On the other hand, if a smaller amount of carbohydrate is eaten, less insulin is required and so any dosing errors that are made will be smaller too, thus allowing for better blood sugar control.
Dr Morrison makes an important distinction between ketosis and diabetic ketoacidosis, explaining that ketosis is a state induced by a relative lack of dietary carbohydrate, whereas diabetic ketoacidosis is a dangerous condition that can arise from a relative lack of insulin in people with type 1 diabetes and also rarely in cases of severe gastroenteritis and as a side effect of SGLT2 inhibitors (gliflozins).
A very low carb, ketogenic approach as advocated by Dr Bernstein is not for everyone. But, good control can also be achieved with a less strict, regular low carb approach. For example, Dr Jorgen Vesti Nielse, using a 20-30g carbs per meal approach, producing long-term, ‘good’ HbA1c control of 46 mmol/mol (6.4%) over 44 months, in both type 1 and type 2 participants. Dr Lois Jovanovic achieves HbA1cs of 34 mmol/mol (5.3%) using a 30-45g carb per meal approach, in type 1, type 2 and gestational diabetes patients alike. She does however use insulin with her non-type 1 patients, and also uses continuous blood glucose monitoring systems with alarms to prevent hypos. Dr Morrison notes that we are not currently able to offer such intensive support in the UK. The current model of the continuous glucose monitoring device, FreeStyle Libre, does not feature an alarm, however a second version is in development.
Although there are many barriers to recommending low carb as a management option for diabetes, Dr Morrison explains that “the back door is open”. The NICE guidelines allow room for diet strategies that are in line with what the patient wants, will look after the patient’s long-term health, avoid hypoglycaemia and achieve good blood sugar control. As strategies can be adapted to patients’ individual needs, there is scope for low carb approaches to be included. Dr Morrison does caution that such an approach might not be applicable for some people with serious mental illnesses, drug addictions or some older people with a shorter life expectancy who may be more resistant to change.
Dr Morrison opines that consistency is the key to good control. She recommends consistent mealtimes, similar macronutrient contents (and not more than 45g of carbs) in each meal, regular exercise and sleep schedules and adequate blood sugar monitoring. A good example of a day’s carb counting would be 15g for breakfast, 45g for lunch and 30g for dinner, she suggests. In contrast, what might be considered a healthy breakfast by some (cereal, milk, banana, toast, marmalade and orange juice) totals around 210g of carbs on its own. Further to this point, Dr Morrison suggests prioritising ‘real food’, explaining that one can get more nutrients and a better reduction in hunger from eating nuts, vegetables and fruits than from high carb foods like bread, pasta, rice and potatoes, all while eating less carbs.
So what can people do to help them reach their HbA1c targets? Dr Morrison says that, depending on the specific HbA1c target a person wishes to aim for, there are a number of strategies people can use, but they may vary from person to person and may depend on how strict or liberal one wants to be. She highlights that in some situations, such as adolescence and during menstruatio, controlling blood sugars can be harder. To improve blood glucose control at a looser level, Dr Morrison recommends occasional weight training, with bits of cardio in betwee, and for women, to use appropriate contraception until blood sugars are stable. Concerning primary school children, Dr Morrison opines that kids can still achieve reasonable blood sugar control even if eating high carb meals at school along with the rest of the children, however more care is needed during adolescence when control becomes harder. There are other situations where additional considerations should be taken into account and Dr Morrison goes through each of these.
Speaking specifically about insulin dosing in type 1 diabetes, Dr Morrison explains that one can achieve precision meal-to-insulin matching by using multiple small-dose injections. This can be just as effective as using a pump and reduces lipohypertrophy (fat forming under the skin due to insulin injection). Dr Morrison notes that there are better types of insulin to use in certain circumstances and that dosing to cover a low carb diet can be quite different from dosing to cover a high carb diet. For those interested, Dr Morrison discusses her thoughts on insulin dosing in greater depth on her blog (diabetesdietblog.com).