Insulin resistance not obesity is often the cause of type 2 diabetes

The overwhelming majority of doctors initially treat diabetes and prediabetes with advice to lose weight and to exercise. The underlying assumption is that diabetes and prediabetes are disorders of lazy, fat people.

There are many people whose diabetes and prediabetes are not the result of excess weight and inactivity. The obvious examples are the lean folk who develop type 2 diabetes. Another example from real life is the 61 year lady with an A1c of 46 (6.4%), just below the 48 (6.5%) that would see her diagnosed as diabetic in the USA and according to WHO criteria. Mary has had an A1c level of 46 for at least five years. She recently completed a three month period on a lower carbohydrate diet during which she lost 9kg (20 pounds) almost ten percent of body weight. Her BMI has moved from 36 to 33. There has been no effect on her A1c level – none at all. It remains at 46.

On this most recent occasion Mary’s fasting insulin level was measured, for the first time. It was 29 mU/L, well above the threshold of 12 or 13 that defines insulin resistance.

Mary demonstrates, rather dramatically, that while insulin resistance and excess stored fat often occur together, reducing fat stores through weight loss does not always reduce insulin resistance.

Mary has four initial options to reduce her insulin resistance. In no particular order these are:

1. Commence taking supplements. There are many choices including Metformin, resveratrol, omega-3 capsules, cinnamon, and olive leaf extracts.

2. Commence regular aerobic (walking, jogging, swimming, cycling) exercise. The best time for this is before the first meal of the day, and that meal should not be dominated by sugar and carbohydrates.

3. Commence weight training. Seriously! Further information about Mary is that her A1c was normal 35-37 (5.2-5.4%) in 2002 and 2004. We have no information yet on the period between 2004 and 2011. The major metabolic event in the interim was menopause, with an accompanying loss of muscle mass. Weight training increases muscle mass. Muscle is a glucose sponge.


4. Try a short duration very low calorie diet. Essentially, this requires Mary to reduce her food intake to one-quarter of her normal level for six days. Then measure fasting glucose and insulin.





Many doctors in New Zealand will not prescribe Metformin for pre-diabetes (or intermediate hyperglycemia as it is also known). They have not caught up with best practice. The relevant best practice article is

It reads, in part, “Intermediate hyperglycaemia is not an approved use for metformin, but it can be prescribed fully subsidised for this indication and there is strong clinical evidence to justify its use. Metformin can be commenced at a low dose, e.g. 500 mg once daily, and increased gradually, e.g. over several weeks, as tolerated to a maximum of 2 g daily if required.”




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