Nutrition Notes

PCOS and Insulin – When Diet Is Not Enough

Polycystic ovary syndrome (PCOS) is one of the most prevalent conditions affecting women’s reproductive health. As practitioners, we are well aware that the body’s hormone network is highly complex and interwoven with many other metabolic pathways, so PCOS is not just a hormonal condition, but an endocrine disorder, as well. Characterized by polycystic ovaries, chronic anovulation, and hyperandrogenism, the leading symptoms of PCOS include irregular menstrual cycles, hirsutism, acne and infertility.

Insulin resistance, compensatory hyperinsulinemia, and reduced insulin clearance are primary metabolic abnormalities associated with the development of PCOS. Compared to age and BMI-matched controls with prediabetes (but no hyperandrogenism and ovulatory disorders), those with PCOS have significantly higher levels of insulin 2 hours following an oral glucose tolerance test and a lower metabolic clearance rate of insulin (MCRI), but a similar degree of insulin sensitivity. Therefore, insulin clearance may be a factor that distinguishes the endocrine dysfunction of PCOS from that of type 2 diabetes.

Similarly, obesity is often a characteristic associated with PCOS and has led many to believe that type 2 diabetes was an underlying cause of PCOS; however, rising numbers of lean women are also presenting with PCOS and confusing the theory that insulin resistance in PCOS is a result of obesity. In a meta-analysis study comparing insulin resistance and sensitivity among obese or non-obese women with PCOS, and obese or non-obese healthy controls, it was found that obesity alone did not have a statistically significant effect on insulin resistance and sensitivity (although obesity certainly increased insulin resistance), but the presence of PCOS had a greater effect on insulin resistance than was caused by obesity alone.

Another study seeking to understand how insulin resistance in PCOS is independent of obesity compared insulin resistance and β cell function in lean PCOS patients with obese PCOS controls. Interestingly, the lean PCOS patients had a similar β cell function and insulin resistance as compared to controls. Additionally, fasting c-peptide and its ratio to glucose were significantly higher in lean patients compared to controls. Together, these results indicate that the insulin metabolism of PCOS is, again, independent of obesity.

Although insulin-sensitizing pharmaceuticals are traditional recommendations for addressing the hyperinsulinemia associated with PCOS, more conservative and natural approaches often focus on a low-sugar, Paleolithic or Ketogenic styles to control blood sugar and insulin levels. While these diets most certainly play a crucial role in optimizing the health of the whole body and balancing blood sugar levels, they are most effective in those who also experience obesity coupled with PCOS. As weight is better managed by rebalancing blood sugar, insulin is better regulated. However, in the lean population with PCOS (and even in many of the obese patients with severe cases of PCOS), a low-sugar diet alone is not enough to address the insulin complications.


Various botanicals and nutraceuticals are helpful in improving insulin resistance and sensitivity when the diet is not enough. In a randomized controlled trial, 50 women with PCOS, insulin resistance, and hyperinsulinemia were given either 4 g per day of myo-inositol or 1500 mg per day of metformin, the commonly prescribed insulin-sensitizing drug. After 6 months, both groups experienced improvement in insulin sensitivity, indicating inositol may be just as effective as metformin for women with PCOS.


Berberine is an isoquinoline derivative alkaloid extracted from various Chinese medicinal herbs that has also been used as an insulin sensitizer. In a randomized controlled trial of 89 women with PCOS and insulin resistance, berberine treatment was compared with metformin for 3 months. It was found that berberine effectively improved body composition, lipid levels (which are often imbalanced in PCOS due to sugar dysregulation), sex hormone-binding globulin, fasting plasma glucose, fasting insulin, and insulin resistance. A meta-analysis and systematic review confirmed the same conclusion that berberine improves insulin resistance and glucose metabolism similar to metformin.


Though not compared to metformin, cinnamon powder has also been shown to improve insulin resistance, glucose metabolism, and lipid profiles in women with PCOS. In a randomized double-blind placebo-controlled clinical trial, 80 women with PCOS were given 1.5 grams per day of cinnamon powder capsules for 12 weeks or a placebo. Improvements were noted in fasting insulin and insulin resistance in those taking the cinnamon compared to placebo.

The clinical outcomes of PCOS, including infertility, severe acne, and hirsutism, are often devastating for women. Hormone balance to address hyperandrogenism is most often the focus of treatment, but as an increasing amount of research points to insulin resistance as an equally influential element of PCOS, a focus on insulin sensitizers can’t be ignored. Diet is a great place to start in rebalancing glucose, but it is often not enough. Inositol, berberine, and cinnamon can also provide the support needed to address insulin resistance in these situations.