New hope from the “seven year switch” in Type 1 diabetes

A team at the University of Exeter Medical School found evidence that the amount of insulin produced declines by almost 50% each year for seven years. At that point, the insulin levels stabilise.

The finding is a major step forward in understanding Type 1 diabetes and contradicts previous beliefs that the insulin produced by people with the condition drops relentlessly with time.  It offers the hope that by understanding what changes after seven years, new strategies could be developed to preserve insulin secreting beta-cells in patients.

The study, published in Diabetes Care, measured C-peptide, which is produced at the same time and in the same quantities as the insulin that regulates our blood sugar. By measuring C-peptide levels in blood or in urine, scientists can tell how much insulin a person is producing themselves, even if they are taking insulin injections as treatment. The team studied 1,549 people with Type 1 diabetes from Exeter, England and Tayside, Scotland in the UNITED study.

Dr Beverley Shields, at the University of Exeter Medical School, who led the research, said: “This finding is really exciting. It suggests that a person with Type 1 diabetes will keep any working beta-cells they still have seven years after diagnosis.  We are not sure why this is; it may well be that there is a small group of “resilient” beta-cells resistant to immune attack and these are left after all the “susceptible” beta-cells are destroyed. Understanding what is special about these “resilient” beta-cells may open new pathways to treatment for Type 1 diabetes.”

Type 1 diabetes affects around 400,000 people in the UK. The disease commonly starts in childhood but can develop at any age, and causes the body’s own immune system to attack and destroy the insulin-producing cells in the pancreas, leaving the patient dependent on life-long insulin injections.

Professor Andrew Hattersley, a Consultant in Diabetes at the Royal Devon and Exeter Hospital and Research Professor at the University of Exeter Medical School, looked forward.  “Now we know there is a “seven year switch”, the next question is why?  Has the immune attack stopped or are we left with “super beta-cells” that can resist the immune onslaught. Any insights into halting the relentless destruction of the precious insulin-producing cells are valuable.  We could not have made this progress without the help of over 1,500 patients. We owe it to them to try to find answers that might help patient care quickly.”

Karen Addington, UK Chief Executive of the type 1 diabetes charity JDRF, said: "These results provide further evidence that the immune system's assault on insulin-producing beta cells is not as complete as we once believed - and may change over time. This further opens the door to identifying ways to preserve insulin production in people diagnosed with or living with type 1 diabetes."

The study was supported by the JDRF, the Department of Health and Social Care and Wellcome Trust through the Health Innovation Challenge Fund and the NIHR.

Helen’s story

Helen Stamp is an example of a person who reached the 7 year switch with lots of her own insulin and that level has stayed stable and helping her since then.

She was diagnosed with Type 1 diabetes at the age of 19 when she was losing weight and had great thirst. She was immediately started on 2 insulin injections a day.  40 years later she is still treated with insulin 4 x/day but tests show her body is still producing about half the insulin her body needs.  This means she takes 23 Units of insulin instead of the 46 units most people with Type 1 diabetes need.  

At times, her insulin levels drop too low, particularly with higher levels of exercise or a lack of routine in her diet. For many people with type 1 diabetes, this would leave them prone to a hypo, with symptoms including dizziness, shakiness or anxiety, but Helen's own insulin production offers some protection from this, shutting down production as needed

This extra insulin has been a help for Helen, a linguist from Williton in Somerset.  She has only has only had one episode when her blood glucose was so low she lost consciousness, normally has near normal blood sugars and has no damage to her kidneys and eyes despite over 40 years of diabetes.  

Helen, 59, said: “I feel like a have a bit of a dodgy thermostat on insulin production. I know if I give it time my own insulin production seems to kick in and my body rights itself so the blood sugar evens out.”

The full paper, ‘C-peptide decline in type 1 diabetes has two phases: an initial exponential fall and a subsequent stable phase’, is published in Diabetes Care. Authors are Beverley M Shields, Timothy J McDonald, Richard Oram, Anita Hill, Michelle Hudson, Pia Leete, Ewan R Pearson, Sarah J Richardson, Noel G Morgan, Andrew T Hattersley on behalf of the TIGI (Type 1 diabetes Immunology and Genetic predictors of endogenous Insulin secretion) consortium.

To find out more about diabetes research at Exeter, visit http://www.exeter.ac.uk/diabetes/ or follow #ExeterDiabetes on Twitter.