Diabetic and Thinking About a GLP-1? Why Your Diabetologist Should Be Involved

If you have type 2 diabetes, a GLP-1 medicine can lower both your weight and your blood sugar, and the American Diabetes Association now names semaglutide or tirzepatide as the preferred medicines for people with diabetes and obesity. But adding one changes how your other diabetes medicines behave. Insulin and sulfonylureas such as glimepiride or gliclazide often need to come down to avoid low sugar, DPP-4 inhibitors such as sitagliptin or teneligliptin should usually stop, and anyone with diabetic eye disease needs their eyes watched. That is why the doctor who manages your diabetes should be part of the decision.

Why diabetes changes the decision

For someone without diabetes, starting a GLP-1 medicine is mostly about appetite, side effects and the dose ladder. With diabetes, the medicine also lowers blood sugar directly, on top of whatever you already take. That is good news, since the 2026 ADA standards say a 5 to 7% loss of body weight improves blood sugar and more than 10% can bring remission for some people (recommendation 8.5). But it means the rest of your prescription was written for a body that is about to change.

India's own diabetes guidance points the same way. The RSSDI's 2022 recommendations say GLP-1 medicines and SGLT2 inhibitors should be preferred as add-ons to metformin in people with diabetes and obesity (RSSDI Clinical Practice Recommendations 2022).

The medicines that may need changing

Check your combination tablets too. Many common Indian diabetes tablets combine two or three medicines in one, such as glimepiride with metformin, or a gliptin with metformin. A sulfonylurea or gliptin hidden inside a combination is easy to miss. Bring every strip, not a list from memory, to your consultation.

Low sugar: know the signs

Both labels warn that using a GLP-1 medicine with insulin or a sulfonylurea raises the risk of low blood sugar, and advise doctors to consider lowering those doses (semaglutide label, tirzepatide label). In the tirzepatide weight-loss trial in people with diabetes, low sugar was reported by 10.3% of those on tirzepatide who were also taking a sulfonylurea, against 2.1% of those on tirzepatide who were not (tirzepatide label).

• Shaking, sweating, a racing heart or sudden hunger.
• Confusion, irritability, blurred vision or slurred speech.
• Waking at night sweaty or with a headache, or bad dreams.

Check your sugar more often in the first weeks and after each dose increase, and ask your doctor for a written plan for treating a low. If you live alone or drive for work, say so: it changes how cautiously the doses are adjusted.

Your eyes: why a fast fall in HbA1c matters

When blood sugar comes down quickly after years of being high, diabetic eye disease can briefly get worse before it gets better. In SUSTAIN-6, eye complications were more common on semaglutide (3% against 1.8%), and a later analysis found most of that excess in people who already had retinopathy, had poor control at the start, were on insulin, and saw their HbA1c fall fast in the first 16 weeks (Vilsbøll et al., Diabetes Obes Metab 2018). The ADA advises checking retinopathy when treatment is intensified with these medicines, and close monitoring for people at higher risk, such as those with diabetes for 10 years or more (ADA 2026, section 12).

In practice: if you have had diabetes for a long time, or have ever been told you have retinopathy, get a dilated eye check before you start, and tell your doctor about any change in vision.

Your kidneys

There is good news here. In the FLOW trial of people with type 2 diabetes and chronic kidney disease, semaglutide lowered the combined risk of kidney failure, a large fall in kidney function, or death from kidney or heart causes by 24% (Perkovic et al., NEJM 2024). The one kidney risk is dehydration: repeated vomiting or loose motions can harm the kidneys, so call your doctor if you cannot keep fluids down (semaglutide label). Ask for kidney function (creatinine, eGFR) and a urine albumin test before starting.

Who should be in the room

1. 1The doctor who manages your diabetes, whether a diabetologist, endocrinologist or physician. In India, GLP-1 medicines are approved for prescription by endocrinologists and internal medicine specialists, and by cardiologists for some uses (Ministry of Health, March 2026). If your diabetes doctor is not the one prescribing it, both need to know what the other is doing.
2. 2Your full medicine list, including combination tablets, BP and cholesterol medicines, and anything for thyroid.
3. 3Recent tests: HbA1c, fasting sugar, creatinine and eGFR, urine albumin, lipid profile, and an eye check if you are due.
4. 4A plan for the first eight weeks: how often to check sugar, the numbers that mean call now, and when the next dose step is.

If you have type 1 diabetes, a GLP-1 medicine is not a substitute for insulin, and any use is a specialist decision. For how semaglutide and tirzepatide compare in diabetes specifically, see how doctors choose between the two.