Blood sugar and insulin resistance in midlife women

Blood sugar control often starts to slip in midlife, and the menopause transition is part of the reason. Changes in body composition and hormones make insulin resistance and prediabetes more likely, usually without any symptoms. The good news is that prediabetes is easy to test for, and the lifestyle changes that prevent type 2 diabetes have some of the strongest evidence in medicine.

What insulin resistance and prediabetes are

Insulin is the hormone that moves glucose (sugar) from your blood into your cells. In insulin resistance, the cells in your muscles, fat and liver do not respond to insulin as well as they should. The pancreas compensates by making more, but over time it may not keep up, and blood glucose rises.

When glucose is higher than normal but not high enough to be type 2 diabetes, that is prediabetes. According to the NIDDK, about 97.6 million US adults had prediabetes in 2021. Most people with it have no symptoms, and people with prediabetes have a high chance of developing type 2 diabetes within 5 to 10 years. Insulin resistance and prediabetes are also linked to high blood pressure, unhealthy cholesterol and triglyceride levels, and fatty liver disease.

Why risk rises in perimenopause

Body composition shifts. In SWAN, a large study of US women through the transition, the rate of fat gain doubled and lean mass began to decline at the start of the transition, continuing until about two years after the final period. Muscle is one of the main places the body stores and uses glucose, so losing it while gaining fat tilts the balance toward insulin resistance. Our guide to metabolism after 40 explains more.

Metabolic syndrome becomes more common. Metabolic syndrome is a cluster of a large waist, high blood pressure, high triglycerides, low HDL cholesterol and high blood sugar. In a SWAN analysis of 949 women followed for nine years, 13.7% had developed it by their final menstrual period. The odds of developing it rose 45% for each year of perimenopause and 24% for each year after menopause, after accounting for aging, body mass index and other factors. Rising levels of bioavailable testosterone and falling levels of sex hormone-binding globulin, typical of the changing hormone balance at this stage, were linked to higher odds.

Other midlife factors pile on. The NIDDK lists risk factors for insulin resistance and prediabetes that include being 35 or older, overweight or a large waist, family history of diabetes, physical inactivity, smoking, a history of gestational diabetes or a baby weighing 9 pounds or more, polycystic ovary syndrome (PCOS), sleep apnea and long-term use of some medicines such as glucocorticoids. Being African American, American Indian, Asian American, Hispanic, Latino or Pacific Islander also raises risk.

Getting tested

The NIDDK says clinicians may test for prediabetes starting at age 35, or earlier if you have overweight or obesity plus other risk factors. If your results are normal but you have risk factors, retesting at least every 3 years is suggested; if you have prediabetes, you should be tested for type 2 diabetes every year.

The American Diabetes Association uses these cutoffs:

Test	Normal	Prediabetes	Diabetes
A1C (average over about 3 months)	Below 5.7%	5.7% to 6.4%	6.5% or higher
Fasting plasma glucose	Below 100 mg/dL	100 to 125 mg/dL	126 mg/dL or higher
2-hour oral glucose tolerance test	Below 140 mg/dL	140 to 199 mg/dL	200 mg/dL or higher

In people with certain health conditions, the A1C may miss prediabetes, so your clinician may use more than one test. Your cholesterol and triglycerides are worth checking at the same time. For the long-term picture, see our guide to type 2 diabetes risk after menopause.

What the evidence shows works

The strongest evidence comes from the Diabetes Prevention Program, a US trial of 3,234 adults with elevated blood glucose. Their average age was 51, and 68% were women. Participants were assigned to a lifestyle program with goals of at least 7% weight loss and at least 150 minutes of physical activity a week, to the drug metformin, or to placebo. Over an average of 2.8 years, the lifestyle program reduced new cases of type 2 diabetes by 58% compared with placebo, and metformin reduced them by 31%. The lifestyle program worked better than the drug.

For food quality, a 2019 series of meta-analyses in The Lancet found in observational studies that people who ate the most fiber had 15% to 30% lower rates of type 2 diabetes and several other diseases than those who ate the least, with the greatest benefit at 25 to 29 grams of fiber a day. Whole grains showed similar results. By contrast, the evidence for choosing foods by glycemic index or glycemic load was rated low to very low certainty. In practice, fiber and whole foods matter more than glycemic index charts.

Eating for steadier blood sugar

Instead of	Try
Sweetened drinks, juice	Water, sparkling water, unsweetened tea or coffee
White bread, white rice	Whole-grain bread, brown rice, quinoa, barley
Sugary cereal	Oatmeal with nuts, or eggs with whole-grain toast
Chips and crackers	Nuts, hummus with vegetables, plain yogurt
Large pasta portion	Smaller portion with beans, vegetables and fish or chicken

A few habits help most:

• Build meals around protein, vegetables and fiber. A meal with protein, fiber and some fat raises blood sugar more gently than refined carbohydrates eaten alone.
• Choose carbohydrates with fiber. Beans, lentils, vegetables, fruit and whole grains are the best sources.
• Cut sugary drinks first. For many people they are the simplest change to make.
• Keep regular meals if long gaps lead to overeating later.
• Drink less alcohol, which adds calories and disrupts sleep.

Food works best alongside activity. Muscles take up glucose when they work, and building muscle gives glucose more places to go. See strength training for women over 40. The NIDDK also lists getting enough sleep as part of preventing and reversing insulin resistance. For a full eating pattern, the Mediterranean diet has good evidence for lowering diabetes risk in women.

Who should be careful

• People taking diabetes medicines, especially insulin or sulfonylureas, who can develop low blood sugar if they cut carbohydrates or fast. Plan changes with your clinician.
• Women with a history of gestational diabetes or PCOS, who are at higher risk and benefit from regular testing.
• Anyone with a history of disordered eating, for whom strict carbohydrate rules or glucose tracking can backfire.

When to see a clinician

Ask for testing if you are 35 or older and have not been tested recently, or sooner if you have risk factors. See a clinician promptly for symptoms of high blood sugar, such as unusual thirst, frequent urination, blurred vision, slow-healing sores or unexplained weight loss. An endocrinologist can help if your blood sugar is hard to control or if you also have PCOS, thyroid disease or other hormone problems. You can find an endocrinologist or menopause-informed clinician.