Attention: The Silent Damage of High Blood Sugar

As a doctor in Australia, I regularly meet people over 30 who feel exhausted, are gaining weight around the middle, and have been told their sugar is “a little high.” They worry about needle injections, nerve pain in their feet, kidney failure, losing their sight, and even problems in the bedroom. They often say: “I don’t want to take medicines forever.” But the real risk is not tablets; it is leaving high blood sugar untreated.

Here is the good news: metformin is one of the safest, most affordable, and most effective tools we have. It has been used for decades, is supported by Australian guidelines, and is on the PBS. If you have type 2 diabetes, prediabetes, polycystic ovary syndrome or insulin resistance, metformin may be the foundation you need.

Interest: What Is Metformin and Why Do Doctors Trust It?

Metformin belongs to the biguanide class. It reduces the amount of glucose your liver releases, improves your body’s sensitivity to insulin, and helps your cells use sugar for energy. Unlike some diabetes drugs, it does not stimulate the pancreas to pump out more insulin, so when used alone it has a very low risk of dangerously low blood sugar. It does not cause weight gain — a huge relief for many adults.

Desire: Protecting Your Kidneys, Nerves, Heart, Teeth and Intimate Health

Weight management: Realistic help, not hype

Many people over 30 struggle with weight, especially around the belly. Excess weight drives insulin resistance, making diabetes harder to control. Metformin is not a “weight-loss pill,” but it can reduce appetite, improve satiety, and support a 1–3 kg loss in some people. More importantly, it prevents the weight gain often seen with insulin or some older diabetes tablets. For patients with PCOS, metformin can improve metabolic health and support weight management when combined with diet and exercise.

Kidney safety: How often should you monitor creatinine on metformin?

One of the biggest fears I hear is kidney damage. Metformin itself does not damage kidneys; however, if kidneys are failing, metformin can build up and cause a rare but serious condition called lactic acidosis. That is why we monitor kidney function with a blood test for creatinine and eGFR.

In practice: if your kidneys are stable and your eGFR is normal, an annual creatinine/eGFR test is usually enough. If you become dehydrated from illness, are starting blood pressure medicines, or have kidney disease, we check more frequently.

Metformin and vitamin B12: the hidden deficiency

Long-term metformin can reduce vitamin B12 absorption in the gut. Low B12 may cause fatigue, pins and needles, memory fog, unsteady walking, or anaemia — symptoms that are sometimes wrongly blamed on diabetes or ageing. I check B12 at baseline and then every one to two years for people on long-term metformin. If your level is low, oral B12 supplements usually correct it. This is simple, cheap, and can prevent nerve symptoms.

Does metformin cause erectile dysfunction?

No. In fact, by improving blood sugar control, blood vessel health and weight, metformin may help protect erectile function. Diabetes itself damages small blood vessels and nerves, which is a major cause of erectile dysfunction in men over 30. Untreated high glucose is the real enemy. One caveat: if metformin leads to untreated B12 deficiency, nerve problems could contribute to sexual dysfunction. That is another reason to monitor B12.

Does metformin interact with other diabetes medications?

Metformin is highly compatible and is often combined with other diabetes medicines. It works in a different way, so it can be used with DPP-4 inhibitors, SGLT2 inhibitors, GLP-1 receptor agonists, sulfonylureas, or insulin. However, combinations with insulin or sulfonylureas increase the risk of low blood sugar, so doses may need adjustment.

Other interactions: large amounts of alcohol, severe dehydration, iodinated contrast dye for scans, or acute illness may require temporarily stopping metformin. Always tell your doctor and radiologist about all medicines.

Metformin and dental health

High blood sugar is bad for your gums and teeth. It feeds bacteria, increases inflammation, and raises the risk of gum disease, loose teeth, dry mouth, and infections. By lowering blood glucose, metformin helps reduce this risk. Some studies suggest better glycaemic control improves periodontal health after dental treatment. If you notice a sore tongue or mouth ulcers, ask about B12, because low B12 can cause glossitis. Keep up regular dental checks.

Paediatric dose of metformin

While this article is for adults over 30, many readers ask about children or grandchildren. In Australia, metformin may be used in children aged 10 years and older with type 2 diabetes, under specialist guidance. The usual starting dose is 500 mg once or twice daily with meals, increased gradually by 500 mg each week, up to a maximum of 2000 mg per day in divided doses. It is not a first-line weight-loss medicine in children.

Action: Ask Your GP About Metformin Today

If you are over 30 and living with type 2 diabetes, prediabetes, PCOS, or insulin resistance, do not wait for damage to appear. Metformin is a prescription-only medicine in Australia, so your next step is a straightforward consultation with your GP. Ask:

• Is metformin suitable for my blood sugar, weight and metabolic health?
• What are my baseline kidney function and vitamin B12 levels?
• How should I start to reduce stomach upset — low dose, with meals, slow increase?
• Should I have an extended-release form if standard metformin upsets my gut?

Start with a low dose, take it with food, and increase slowly. Use it as part of a daily plan that includes walking, fewer sugary drinks, and regular GP reviews. Metformin is not a cure, but it is one of the best protective tools we have. Every day of better glucose control helps protect your heart, kidneys, eyes, gums, nerves and sexual function.

Take the first step today: book a GP appointment and ask whether you are eligible for a PBS-subsidised metformin prescription.