Approximately 30% of diabetes cases in young, non-obese people are caused by genetic mutations, according to the Japan Diabetes Society.

Recently NHK News on-line reported the following:

若く肥満ない人の糖尿病 約3割は遺伝子変異が原因 糖尿病学会

2025年11月20日午前6時12分

医療・健康

35歳未満で糖尿病と診断され、肥満などがない人の、およそ3割は、遺伝子の変異が病気の原因だとする調査結果を、日本糖尿病学会のグループがまとめました。

糖尿病は主に、自分の免疫などが原因で発症する1型と、加齢や肥満、体質などが影響して発症する2型がありますが、いずれにもあてはまらず、若い年齢で診断される患者も少なくありません。

日本糖尿病学会の研究グループは、全国の医療機関で35歳未満で診断された患者のうち、1型ではなく肥満もない232人を対象に、インスリンの分泌などに関わる11種類の遺伝子を解析しました。

その結果、全体の28.9％にあたる67人は、いずれかの遺伝子に変異が見つかり、こうした遺伝子がうまく働いていないことが糖尿病の原因とみられるとわかったということです。

67人の多くはインスリン注射などをしていましたが、原因となる遺伝子がわかることで、血糖値が高めでも症状が出にくいタイプで、治療が必要ないとわかったり、注射から飲み薬に切り替えられたりするなど、適切な治療を提案できることがわかったとしています。

グループの推計では、こうした患者は国内に数万人いるとみられるということです。

研究グループの代表で京都大学の稲垣暢也名誉教授は「糖尿病の遺伝子検査は保険適用されておらず、原因がわからないまま治療を受けているケースは少なくない。適切な治療につなげるため、検査の保険適用を求めたい」と話していました。

遺伝子変異が原因のケース 検査は広く行われず

糖尿病は、血糖値を下げる働きのあるインスリンが、すい臓で十分作られなかったり働かなかったりして血糖値が高くなる病気で、厚生労働省の平成28年の推計では、国内の患者はおよそ1000万人とされています。

初期症状として、のどの渇きや疲労感などが出るほか、血糖値が高い状態が続くと血管が傷ついて心臓病や腎臓病などのリスクが高まり、人工透析が必要になることもあります。

糖尿病には主に、▽インスリンを作る細胞を自分の免疫が攻撃してしまうなどして発症する1型と、▽加齢や肥満、体質などが影響して発症する2型があり、原因に応じた治療が行われます。

一般的には、運動や食事の改善が行われ、血糖値が下がらない場合はインスリン注射や飲み薬で治療します。

糖尿病にはこのほか、インスリンの分泌などに関わる遺伝子の変異が原因のケースもありますが、日本糖尿病学会によりますと、国内ではこうした遺伝子を調べる検査に公的な医療保険が適用されておらず、広く行われていないため、患者の詳しい実態はわかっていないということです。

Translation

Approximately 30% of diabetes cases in young, non-obese people are caused by genetic mutations, according to the Japan Diabetes Society.

A group from the Japan Diabetes Society had compiled survey results suggesting that genetic mutations were the cause of approximately 30% of people under the age of 35 who were not obese yet diagnosed with diabetes.

Diabetes was primarily divided into type 1, which was caused by factors such as the immune system, and type 2, which was caused by aging, obesity, or physical constitution. However, many patients did not fit either category and were diagnosed at a young age.

A research group from the Japan Diabetes Society at medical institutions nationwide studied 232 non-obese and non-type 1 diabetic patients under the age of 35 in order to analyze 11 genes related to insulin secretion and other processes.

The results showed that 67 patients, or 28.9% of the total, their genes weren't working smoothly​, suggesting that the malfunction of these genes could the cause of diabetes.

While many of these 67 people were receiving insulin injections, by identifying the causative genes, it was discovered that some people had a type of diabetes that was less likely to cause symptoms even when their blood sugar levels were high and therefore no treatment was necessary, or they could switch from injections to oral medication etc., making it possible to suggest different appropriate treatments.

The group estimated that there were tens of thousands of such patients in Japan.

Research group leader and Kyoto University Professor Emeritus Nobuya Inagaki (稲垣暢也) said, "Genetic testing for diabetes is not covered by insurance, and in many cases, patients are receiving treatment without knowing the cause. I would like to request insurance coverage to do testing so that patients can receive the right treatment."

Cases Caused by Genetic Mutations: Testing Not Widely Carried Out

Diabetes was a disease in which the pancreas did not produce enough insulin which lowered blood sugar levels, or did not function properly causing blood sugar levels to rise. According to a 2016 estimate by the Ministry of Health, Labor and Welfare, there were approximately 10 million patients in Japan.

Initial symptoms included thirst and fatigue. Prolonged high blood sugar levels could damage blood vessels, increasing the risk of heart disease and kidney disease, and might even require dialysis.

There were two main types of diabetes: type 1, which occurs when the body's own immune system attacks insulin-producing cells, and type 2, which develops as a result of aging, obesity, or physical make-up. Treatment was based on the cause.

Generally, treatment involved exercise and dietary changes, and if blood sugar levels did not decrease, insulin injections or oral medication were used.

Diabetes could also be caused by mutations in genes related to insulin secretion, but according to the Japan Diabetes Society, testing for these genes would not be covered by public health insurance in Japan and was not widely available, so the details of the patient's actual condition were not known.

              So, a research group in Japan has studied 232 non-obese and non-type 1 diabetic patients who are under the age of 35 so as to analyze 11 genes related to insulin secretion etc. As diabetes could also be caused by mutations in genes related to insulin secretion, testing for these genes would help identify the causative genes and make it possible to suggest more appropriate treatments.