Protecting your remaining beta cells in type 1 diabetes

Yes, at the time of diagnosis most people still have 10–50% of their beta cells working, the proportion varying with age (young children lose more, young adults may retain more) [1]. Symptoms appear when beta cell mass drops below a critical threshold, which varies from person to person. C-peptide measured in the blood confirms the presence of some remaining working beta cells. Values above 0.2 nmol/L indicate significant residual insulin production [2].

These remaining beta cells are very valuable even if they do not produce enough insulin to provide complete independence. They offer a kind of buffering system that smooths out blood glucose fluctuations, reducing the risk of both hypoglycaemia and ketoacidosis [3]. Glycaemic control is therefore easier to achieve. Studies show that people with residual beta cell function have a lower risk of long-term (chronic) complications [4].

The single most important protective factor is glycaemic control [5]. Persistently high blood glucose is toxic to beta cells, and the effect is proportional to the level and duration of the hyperglycaemia [6]. Aim for blood glucose between 70–140 mg/dl (3.9–7.8 mmol/L) as much as possible. Avoid episodes of ketoacidosis at all costs. Acidosis and dehydration are extremely toxic to beta cells [7].

Adequate doses of external insulin give the beta cells a rest, reducing the stress placed on them and the strain they endure while working. Do not try to "train" your pancreas by under-dosing insulin. Studies show that starting intensive insulin treatment early maximises the chances of preserving residual beta cell function [5].

Yes, glycaemic control is the most powerful protective factor for your remaining beta cells [5]. Glucotoxicity, the toxic effect of hyperglycaemia on beta cells, accelerates apoptosis (programmed cell death) and reduces their capacity to secrete insulin [6]. Every episode of severe hyperglycaemia can contribute to the permanent loss of precious beta cells.

The DCCT study showed that intensive therapy, with stricter glycaemic targets, slows the rate of C-peptide decline, so it persists for longer [5]. People with HbA1c below 7% (53 mmol/mol) in the first year after diagnosis maintain better residual beta cell function in the long term [8].

Yes, there are medicines being studied to preserve beta cells, although most are still experimental [9]. Teplizumab (Tzield) can delay the loss of beta cell function by 2–3 years when given in the early stages [10]. The prohibitive cost (over 200,000 euros) and limited availability are major barriers.

Other therapies under study include monoclonal antibodies (anti-CD3, anti-CD20), selective immunosuppressants (sirolimus, tacrolimus) and tolerance-induction therapies (oral insulin, GAD vaccine) [9]. Taking part in clinical trials offers access to these experimental therapies.

Residual beta cells can survive for years or even decades after diagnosis, although their output becomes clinically negligible [11]. Studies using ultrasensitive C-peptide assays show that around 40% of people with type 1 diabetes of more than 10 years still have minimal detectable insulin production [12]. This tiny output, even when it is insufficient for glycaemic control, is beneficial.

Factors that influence beta cell survival include an older age at onset, better glycaemic control, the absence of additional autoimmune diseases and, possibly, protective genetic factors [11]. Beta cells may persist in a "dormant" state, with minimal output, but still viable [13]. Current research is exploring how to reactivate these dormant cells.

Residual beta cell function is measured by assaying C-peptide, a molecule released by beta cells in amounts equal to insulin [2]. Regardless of any insulin injected from outside, C-peptide reflects only your own (endogenous) production. The test is generally done in the morning, fasting (basal value) or after stimulation with a standardised mixed meal (more sensitive) [2].

In the context of type 1 diabetes, C-peptide values are interpreted as below 0.02 ng/ml for total absence; 0.02–0.2 ng/ml for minimal function; and above 0.2 ng/ml for good secretory function (in context) [2]. Annual testing in the first five years can help document the decline [12]. The cost of the test is reasonable.

Preserving any residual beta cell function, even a minimal amount, brings major benefits [3]. People with detectable C-peptide have 50% fewer severe hypoglycaemias, a reduced risk of ketoacidosis, lower glycaemic variability and a better HbA1c, all with less effort [3]. Residual function provides a safety net that protects you in difficult situations.

In the long term, the presence of C-peptide is associated with a delay in the onset of chronic complications [4]. That is why any strategy that preserves beta cell function, even partially, is worth considering.

Diet can influence beta cell survival through several mechanisms. A moderate low-carb diet (100–150 g of carbohydrate a day) reduces the need for insulin and the secretory stress on beta cells [6]. Avoiding post-meal blood glucose spikes through smart food choices (low glycaemic index, fibre, protein) minimises glucotoxicity [6].

Intermittent fasting or intermittent calorie restriction are being studied for their regenerative potential, but the evidence is preliminary [14]. Avoid extreme diets, which can destabilise glycaemic control.