Daijiworld Media Network - New Delhi

New Delhi, Oct 13: ‘Double diabetes’ may sound like a person has been diagnosed with two different types of diabetes. However, the term refers to a condition in which a person with type 1 diabetes also develops insulin resistance, a characteristic commonly associated with type 2 diabetes.

The combination can make blood sugar levels more difficult to control and increase the amount of insulin required to manage the condition. Although double diabetes is not officially recognised as a separate type of diabetes, it is an increasingly studied clinical concept because of its potential implications for long-term health.

Dr Aarti Ullal, physician and diabetologist at Gleneagles Hospital, Parel, explained that the condition involves the coexistence of type 1 diabetes and insulin resistance.

“It means the body needs more insulin to control blood sugar. It is not a separate type of diabetes. The term mainly describes this combination of conditions,” Dr Ullal told indianexpress.com.

Medical research published in the journal Diabetologia has also examined the relationship between insulin resistance and type 1 diabetes, highlighting the possible implications for cardiovascular health and diabetes-related complications.

Does double diabetes mean having both type 1 and type 2 diabetes?

A person with double diabetes continues to have type 1 diabetes but develops significant insulin resistance alongside it. This does not necessarily mean that the person has developed two entirely separate forms of diabetes.

In type 1 diabetes, the immune system mistakenly attacks the insulin-producing beta cells in the pancreas, leaving the body with little or no ability to produce insulin. These patients depend on insulin treatment to regulate their blood glucose levels.

Insulin resistance, meanwhile, occurs when the body's cells respond less effectively to insulin. As a result, more insulin is needed to help glucose move from the bloodstream into the cells.

When insulin resistance develops in someone who already has type 1 diabetes, the person may require higher insulin doses to achieve adequate blood sugar control.

A review published in Diabetologia in 2013 examined this combination and its possible links to weight gain, family history, metabolic health and cardiovascular disease. A further review published in 2024 explored the difficulties in defining and identifying double diabetes, noting that insulin resistance is central to the condition.

What causes double diabetes?

The development of double diabetes is believed to involve several interacting factors rather than a single cause.

Excess body weight and abdominal fat can contribute to insulin resistance. People with type 1 diabetes who become overweight or develop obesity may therefore experience greater difficulty maintaining blood sugar control.

Genetic susceptibility may also play a role. Research has suggested that people with type 1 diabetes who have a family history of type 2 diabetes may be more likely to develop features associated with insulin resistance.

Lifestyle factors, including physical inactivity and dietary habits that contribute to excess weight, may further influence metabolic health.

Researchers have also investigated the relationship between insulin treatment, changes in body weight and insulin sensitivity. However, the mechanisms are complex, and weight gain during treatment does not automatically mean that a person has developed double diabetes.

The condition can occur in people with different body weights, and obesity alone is not sufficient to establish the diagnosis.

What are the warning signs?

Double diabetes may not produce symptoms that clearly distinguish it from type 1 diabetes. Instead, doctors may suspect insulin resistance when a patient experiences increasing difficulty controlling blood glucose despite receiving insulin treatment.

Possible indicators include persistently elevated blood sugar levels, increasing insulin requirements, excess weight, abdominal obesity, high blood pressure and abnormal cholesterol or triglyceride levels.

However, requiring higher insulin doses does not by itself confirm insulin resistance. Insulin requirements can also change because of illness, hormonal changes, medication, diet, physical activity and other factors.

A medical assessment is therefore necessary to determine whether insulin resistance or another issue is contributing to poor blood sugar control.

Why is double diabetes a concern?

The coexistence of type 1 diabetes and insulin resistance may increase the risk of complications affecting the heart, blood vessels, kidneys and eyes.

A review published in Diabetes, Obesity and Metabolism in 2019 reported that people with type 1 diabetes who display features of double diabetes may face a higher risk of future diabetes-related complications, potentially independent of average blood glucose levels.

Research published in Diabetes Care in 2007 also found that insulin resistance, estimated using a measure known as the estimated glucose disposal rate, was associated with an increased risk of retinopathy, kidney disease and cardiovascular disease among people with type 1 diabetes.

These findings underline the importance of addressing metabolic risk factors alongside blood glucose management. However, the precise level of additional risk attributable to double diabetes remains an area of ongoing research.

How is double diabetes diagnosed?

There is no universally accepted diagnostic definition of double diabetes. Doctors generally consider a combination of clinical history, insulin requirements, body weight, blood pressure and laboratory findings when assessing possible insulin resistance in a person with type 1 diabetes.

Tests may include measurements of blood glucose and glycated haemoglobin (HbA1c), which reflects average blood glucose levels over approximately two to three months. Cholesterol and triglyceride measurements may also help identify associated metabolic risk factors.

Doctors may additionally use clinical indicators of insulin sensitivity, including the estimated glucose disposal rate, depending on the circumstances.

Because people with type 1 diabetes receive insulin from an external source, assessing insulin resistance can be more complicated than in people who do not require insulin treatment. No single test or insulin-dose threshold establishes double diabetes in every patient.

Can double diabetes be managed?

Management focuses on improving insulin sensitivity, maintaining appropriate blood glucose levels and reducing the risk of long-term complications.

Doctors may review insulin doses and treatment regimens, while recommending regular physical activity, a balanced diet and weight management where appropriate.

Monitoring blood pressure, cholesterol levels and kidney health is also important because cardiovascular and other metabolic risks may accompany insulin resistance.

In selected cases, specialists may consider additional medicines used in type 2 diabetes alongside insulin. However, such treatment must be individualised, as not all medicines are suitable for people with type 1 diabetes and some carry specific risks.

Insulin must not be stopped or reduced without medical advice. People with type 1 diabetes remain dependent on insulin, and inadequate insulin treatment can lead to diabetic ketoacidosis, a potentially life-threatening emergency.

What does the research say?

A 2013 review in Diabetologia examined the mechanisms and cardiovascular implications of insulin resistance in type 1 diabetes. A 2019 review in Diabetes, Obesity and Metabolism further discussed double diabetes as a potentially higher-risk subgroup of patients. A 2024 review in Cardiovascular Diabetology revisited the condition's definition, potential causes, clinical recognition and treatment approaches.

Together, these studies highlight the importance of identifying insulin resistance in people with type 1 diabetes while recognising that double diabetes does not yet have a universally accepted diagnostic definition.

Doctors emphasise that treatment should be tailored to the individual, with attention to blood sugar control, weight, cardiovascular risk factors and overall metabolic health.