Practical implementation of automated closed-loop insulin delivery: A French position statement.

Automated closed-loop (CL) insulin therapy has come of age. This major technological advance is expected to significantly improve the quality of care for adults, adolescents and children with type 1 diabetes. To improve access to this innovation for both patients and healthcare professionals (HCPs), and to promote adherence to its requirements in terms of safety, regulations, ethics and practice, the French Diabetes Society (SFD) brought together a French Working Group of experts to discuss the current practical consensus. The result is the present statement describing the indications for CL therapy with emphasis on the idea that treatment expectations must be clearly defined in advance. Specifications for expert care centres in charge of initiating the treatment were also proposed. Great importance was also attached to the crucial place of high-quality training for patients and healthcare professionals. Long-term follow-up should collect not only metabolic and clinical results, but also indicators related to psychosocial and human factors. Overall, this national consensus statement aims to promote the introduction of marketed CL devices into standard clinical practice.

Nuclear power plant: state of knowledge of the population living in the area of the Cattenom special intervention plan. A cross-sectional study.

In France information campaigns are periodically conducted within a 10 km radius of nuclear power plants on the protective actions to be adopted in the event of a nuclear accident. The aim of this study was to assess the knowledge of the inhabitants of the Cattenom PPI area on the recommended actions to be adopted in the event of a nuclear accident after the information campaign that took place from 2016 to 2017 and compare its results with a similar study carried out before the information campaign. We performed a cross-sectional study in the Cattenom PPI area after the 2016-2017 information campaign. We administered questionnaires in ten municipalities selected by lot. These questionnaires contained queries on the general protective actions and required approach to taking potassium iodide (KI). The results obtained were compared with the results of a study conducted before the information campaign in the same area. Out of 200 questionnaires administered, 122 people responded. Only 40% of respondents remembered the information campaign. Only 16% knew all of the recommended protective actions. 78% of households had KI and only 60% knew the objective of KI intake. Compared to the results of the study before the information campaign, KI coverage was better (69% versus 78%, p = 0.02) and the dosage was better known (16% versus 28%, p = 0.0003). This study provides an overview of the effectiveness of information campaigns on the procedure in the event of a nuclear accident. This study highlights the insufficient knowledge of people living in the Cattenom PPI area.

Efficacy and adherence of glucagon-like peptide-1 receptor agonist treatment in patients with type 2 diabetes mellitus in real-life settings.

Despite the availability of a large number of therapeutic options throughout the world, rates of optimal glycaemic control in adult patients with type 2 diabetes mellitus remain low. Delays in treatment intensification to insulin and low adherence to insulin regimes, which are well-documented contributors to poor glycaemic control, are in many cases driven by fear of hypoglycaemic events, weight gain and injections. Over the last 10 years, injectable glucagon-like peptide-1 receptor agonists (GLP1-RAs) have emerged as alternatives to basal insulin for treatment intensification in patients inadequately controlled with oral antidiabetic drugs. As a class, GLP1-RAs are associated with weight loss and fewer hypoglycaemic events than insulin. In addition, some of them are available in once-a-week formulations and therefore require fewer injections. However, as randomized controlled trials are not representative of everyday practice, physicians should consider the results of real-life studies to guide their treatment decisions. In this review, while significant variations in efficacy, tolerability and adherence data were noted from one study to another, rates of glycaemic control overall were low. Indeed, our present analysis has suggested that regular re-evaluations of treatment, including response, tolerability, adherence, cost and quality of life, are necessary.

Practical implementation, education and interpretation guidelines for continuous glucose monitoring: A French position statement.

The use by diabetes patients of real-time continuous interstitial glucose monitoring (CGM) or the FreeStyle Libre® (FSL) flash glucose monitoring (FGM) system is becoming widespread and has changed diabetic practice. The working group bringing together a number of French experts has proposed the present practical consensus. Training of professionals and patient education are crucial for the success of CGM. Also, institutional recommendations must pay particular attention to the indications for and reimbursement of CGM devices in populations at risk of hypoglycaemia. The rules of good practice for CGM are the precursors of those that need to be enacted, given the oncoming emergence of artificial pancreas devices. It is necessary to have software combining user-friendliness, multiplatform usage and average glucose profile (AGP) presentation, while integrating glucose and insulin data as well as events. Expression of CGM data must strive for standardization that facilitates patient phenotyping and their follow-up, while integrating indicators of variability. The introduction of CGM involves a transformation of treatment support, rendering it longer and more complex as it also includes specific educational and technical dimensions. This complexity must be taken into account in discussions of organization of diabetes care.

Sex hormone levels are not associated with progression of renal disease in male patients with T2DM.

BACKGROUND: Greater renal function decline (RFD) in type 2 diabetes (T2DM) has been suggested in men compared with women, and imbalances in estrogen/androgen levels have been associated with cardiovascular disease mortality in elderly men, but it remains unclear whether sex hormone disequilibrium is related to diabetic nephropathy (DN) in men with T2DM. OBJECTIVE: This study examined the relationship between sex steroid concentrations and renal outcomes in male T2DM patients. POPULATION AND METHODS: Total testosterone (T), total estradiol (E2), sex hormone-binding globulin (SHBG), and total and calculated free (cf) E2/T ratios were compared in 735 male T2DM patients with (n=513) and without (n=222) DN, using a cross-sectional approach. Also, in a pilot complementary prospective nested case-control cohort, total E2/total T and cfE2/cfT were evaluated according to a hard renal outcome (HRO): end-stage renal disease/doubling of baseline serum creatinine (36 HRO cases, 72 HRO controls) and rate of eGFR decline (68 rapid vs 68 slow RFD). RESULT: With the cross-sectional approach, E2 and cfE2 were higher in DN cases vs DN controls (95.5 vs 86.8pmol/L [P=0.0246] and 2.59 vs 2.36pmol/L [P=0.005], respectively). The difference in E2 persisted on multivariate analysis. In the prospective approach, E2 and T concentrations, and total E2/total T and cfE2/cfT2 ratios did not differ in HRO cases vs controls or in patients with rapid vs slow RFD. CONCLUSION: Although positively related to DN in the cross-sectional analysis, progression of renal disease in male patients with T2DM was not related to either sex hormone levels or aromatase index as reflected by E2/T ratio.

Indication, organization, practical implementation and interpretation guidelines for retrospective CGM recording: A French position statement.

AIM: The benefits of retrospective continuous glucose monitoring (retroCGM) recording have been widely explored in clinical studies, and many diabetes physicians routinely use this examination. However, the method of interpretation of CGM recordings has never been precisely described. METHOD: An expert French panel of physicians met for two days to discuss several aspects of retroCGM use and to produce a position statement. RESULTS: The guidelines cover the indications for retroCGM, the general organization and practical implementation of CGM recordings, a description of the different devices available and guidelines for the interpretation of retroCGM recordings. CONCLUSION: This consensus document should help clinicians in the proper use of retroCGM.

Safety and efficacy of once-weekly dulaglutide versus sitagliptin after 2 years in metformin-treated patients with type 2 diabetes (AWARD-5): a randomized, phase III study.

AIMS: To compare the once-weekly glucagon-like peptide-1 (GLP-1) receptor dulaglutide with the dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin after 104 weeks of treatment. METHODS: This AWARD-5 study was a multicentre, double-blind trial that randomized participants to dulaglutide (1.5 or 0.75 mg) or sitagliptin 100 mg for 104 weeks or placebo (reported separately) for 26 weeks. Change in glycated haemoglobin (HbA1c) concentration from baseline was the primary efficacy measure. A total of 1098 participants with HbA1c concentrations ≥7.0% (≥53.0 mmol/mol) and ≤9.5% (≤80.3 mmol/mol) were randomized, and 657 (59.8%) completed the study. We report results for dulaglutide and sitagliptin at the final endpoint. RESULTS: Changes in HbA1c at 104 weeks were (least squares mean ± standard error) -0.99 ± 0.06% (-10.82 ± 0.66 mmol/mol), -0.71 ± 0.07% (-7.76 ± 0.77 mmol/mol) and -0.32 ± 0.06% (-3.50 ± 0.66 mmol/mol) for dulaglutide 1.5 mg, dulaglutide 0.75 mg and sitagliptin, respectively (p < 0.001, both dulaglutide doses vs sitagliptin). Weight loss was greater with dulaglutide 1.5 mg (p < 0.001) and similar with 0.75 mg versus sitagliptin (2.88 ± 0.25, 2.39 ± 0.26 and 1.75 ± 0.25 kg, respectively). Gastrointestinal adverse events were more common with dulaglutide 1.5 and 0.75 mg versus sitagliptin (nausea 17 and 15% vs 7%, diarrhoea 16 and 12% vs 6%, vomiting 14 and 8% vs 4% respectively). Pancreatic, thyroid, cardiovascular and hypersensitivity safety were similar across groups. CONCLUSIONS: Dulaglutide doses provided superior glycaemic control and dulaglutide 1.5 mg resulted in greater weight reduction versus sitagliptin at 104 weeks, with acceptable safety.

Treatment escalation options for patients with type 2 diabetes after failure of exenatide twice daily or glimepiride added to metformin: results from the prospective European Exenatide (EUREXA) study.

AIMS: To evaluate third-line thiazolidinedione (TZD) or glimepiride therapy in patients inadequately controlled on metformin + exenatide twice daily, and third-line exenatide twice daily in patients inadequately controlled on metformin + glimepiride. METHODS: In this randomized, open-label, multicentre trial, 144 patients with type 2 diabetes inadequately controlled [glycated haemoglobin (HbA1c) >9% (75 mmol/mol) after 3 months' treatment or >7% (53 mmol/mol) at two consecutive visits 3 months apart, after 6 months' treatment] on metformin + exenatide twice daily were re-randomized to add-on TZD or glimepiride, and 166 patients inadequately controlled on metformin + glimepiride received add-on exenatide twice daily. Changes in HbA1c, body mass index (BMI), lipids, hypoglycaemia and vital signs were evaluated. RESULTS: The median duration of triple therapy was ∼2 years. In patients inadequately controlled on metformin + exenatide twice daily, add-on TZD decreased HbA1c levels significantly better than add-on glimepiride: 130-week difference 0.48% [95% confidence interval (CI) 0.19-0.77] or 5.2 mmol/mol (95% CI 2.1-8.4; p = 0.001), but with significantly increased BMI and systolic blood pressure. The ratio of documented symptomatic (blood glucose ≤70 mg/dl [3.9 mmol/l]) hypoglycaemia rates for add-on glimepiride to add-on TZD was 8.48 (p < 0.0001). Add-on exenatide twice daily after metformin + glimepiride significantly reduced HbA1c levels: mean [standard deviation (s.d.)] change from baseline -0.35 (0.89)% [-3.8 (9.7) mmol/mol] and BMI: mean (s.d.) change from baseline -0.82 (1.9) kg/m(2) at 130 weeks, with a slightly increased rate of documented symptomatic hypoglycaemia from metformin + glimepiride (ratio 1.49). CONCLUSIONS: TZD, but not glimepiride, was an effective and well tolerated third-line therapy in patients without glycaemic control after long-term therapy with metformin + exenatide twice daily. Exenatide twice daily was an effective and well tolerated third-line therapy in patients inadequately controlled on metformin + glimepiride.

Telemedicine and type 1 diabetes: is technology per se sufficient to improve glycaemic control?

AIM: In the TELEDIAB-1 study, the Diabeo system (a smartphone coupled to a website) improved HbA1c by 0.9% vs controls in patients with chronic, poorly controlled type 1 diabetes. The system provided two main functions: automated advice on the insulin doses required; and remote monitoring by teleconsultation. The question is: how much did each function contribute to the improvement in HbA1c? METHODS: Each patient received a smartphone with an insulin dose advisor (IDA) and with (G3 group) or without (G2 group) the telemonitoring/teleconsultation function. Patients were classified as "high users" if the proportion of "informed" meals using the IDA exceeded 67% (median) and as "low users" if not. Also analyzed was the respective impact of the IDA function and teleconsultations on the final HbA1c levels. RESULTS: Among the high users, the proportion of informed meals remained stable from baseline to the end of the study 6months later (from 78.1±21.5% to 73.8±25.1%; P=0.107), but decreased in the low users (from 36.6±29.4% to 26.7±28.4%; P=0.005). As expected, HbA1c improved in high users from 8.7% [range: 8.3-9.2%] to 8.2% [range: 7.8-8.7%] in patients with (n=26) vs without (n=30) the benefit of telemonitoring/teleconsultation (-0.49±0.60% vs -0.52±0.73%, respectively; P=0.879). However, although HbA1c also improved in low users from 9.0% [8.5-10.1] to 8.5% [7.9-9.6], those receiving support via teleconsultation tended to show greater improvement than the others (-0.93±0.97 vs -0.46±1.05, respectively; P=0.084). CONCLUSION: The Diabeo system improved glycaemic control in both high and low users who avidly used the IDA function, while the greatest improvement was seen in the low users who had the motivational support of teleconsultations.

[Concerns about glycated haemoglobin and the limitations of its interpretations]. / A propos de l'hémoglobine glyquée: les limites de son interpretation.

Determining the level of glycated haemoglobin, in particular its major fraction called HbA(1c), is an attractive tool in the management of diabetic patients. In fact, it provides a global evaluation of the glycemic control's level through the past 8-12 weeks. However, this tool must be used with caution. First of all, it does not allow to examine the glycemic kinetics since it represents a glycemic average. Secondly, it does not allow to appreciate the glycemic evolution through the full day. This dosage needs then sometimes to be complemented by fingersticks blood glucose testing. Last but not least, caution is advised in interpreting the results because a number of physiological, pathological and technical factors might interfere with HbA(1c) measurement. It is therefore important that physicians keep a critical view of the values obtained. The paper reviews the different methods used to determine the level of glycated haemoglobin and their limitations. It also emphasizes the medical situations in which over- and under-estimation of the real HbA(1c) value could occur. It does not address the specific issue of the new expression values of HbA(1c) in mmol/mol instead of %. Moreover, the medical situations in which over- and underestimation of the real HbA(1c) value could occur will be described.

Continuous glucose profiles with vildagliptin versus sitagliptin in add-on to metformin: results from the randomized Optima study.

AIM: To compare continuous glucose monitoring (CGM) profiles on vildagliptin versus sitagliptin in addition to metformin, in patients with inadequately controlled type 2 diabetes mellitus (HbA(1c) 6.5-8.0%). METHODS: A multicenter, prospective, randomised, open-label study with blinded endpoint analysis. CGM data acquired over three days--firstly on metformin alone and then 8 weeks after the addition of either vildagliptin (n=14) or sitagliptin (n=16)--were blinded and analyzed centrally. RESULTS: In comparable populations with a mean baseline HbA1c of 7.1%, 24-hour glucose variability--measured by mean amplitude of glucose excursions and standard deviation of mean glucose concentration--showed similar improvement on both drugs versus metformin alone. In contrast, a series of predefined parameters reflecting daily glycaemic control--mean 24-hour blood glucose concentration, and the times spent in the optimal glycaemic range (70-140 mg/dL) and above the hyperglycaemic thresholds of 140 and 180 mg/dL together with the corresponding AUC values--were significantly improved from baseline only in the vildagliptin arm. In addition, overall hyperglycaemia (AUC[24 h] > 100 mg/dL) significantly dropped from baseline on vildagliptin [-37%] but not on sitagliptin [-9%], while postprandial hyperglycaemia (AUC[0-4 h] × 3) was significantly reduced on both, and basal hyperglycaemia (overall--postprandial hyperglycaemia was reduced only on vildagliptin [-41%; P = 0.04]). CONCLUSIONS: The addition of a DPP-4 inhibitor significantly reduced glycaemic variability with no difference between the two drugs. However, vildagliptin induced better circadian glycaemic control than sitagliptin with a significant decrease on overall hyperglycemia, mainly driven by reduction on basal hyperglycaemia.

Gastric electrical stimulation for the treatment of diabetic gastroparesis.

Diabetic gastroparesis is a component of autonomic neuropathy, and is the most common manifestation of gastrointestinal neuropathy. Diabetes is responsible for about one quarter of gastroparesis. The upper gastrointestinal symptoms are often non-specific and dominated by nausea, vomiting, early satiety, fullness, bloating. We also have to look for diabetic gastroparesis in case of metabolic instability, such as postprandial hypoglycaemia. The pathophysiology of diabetic gastroparesis is complex, partly due to a vagus nerve damage, but also to changes in secretion of hormones such as motilin and ghrelin. A decrease in the stem cell factor (SCF), growth factor for cells of Cajal (gastric pacemaker), was found in subjects with diabetic gastroparesis. These abnormalities lead to an excessive relaxation in the corpus, a hypomotility of antrum, a desynchronization antrum-duodenum-pylorus, and finally an abnormal duodenal motility. The treatment of diabetic gastroparesis is based on diabetes control, and split meals by reducing the fiber content and fat from the diet. The antiemetic and prokinetic agents should be tested primarily in people with nausea and vomiting. Finally, after failure of conventional measures, the use of gastric neuromodulation is an effective alternative, with well-defined indications. Introduced in the 1970s, this technology works by applying electrical stimulation continues at the gastric antrum, particularly in patients whose gastric symptoms are refractory to other therapies. Its efficacy has been recently reported in different causes of gastroparesis, especially in diabetes. Gastric emptying based on gastric scintigraphy, gastrointestinal symptoms, biological markers of glycaemic control and quality of life are partly improved, but not normalized. Finally, a heavy nutritional care is sometimes necessary in the most severe forms. The enteral route should be preferred (nasojejunal and jejunostomy if possible efficiency). However, in case of failure especially in patients with small bowel neuropathy, the long-term parenteral nutrition is sometimes required.

[Wolfram syndrome: clinical and genetic analysis in two sisters]. / Le syndrome de Wolfram : mise au point clinique et génétique à propos du cas de deux sœurs.

Wolfram syndrome is a severe genetic disorder defined by the association of diabetes mellitus, optic atrophy, deafness, and diabetes insipidus. Two sisters complained of progressive visual loss. Fundus examination evidenced optic atrophy. Their past medical history revealed diabetes mellitus and deafness since childhood. The association of these symptoms made the diagnosis of Wolfram syndrome possible. It was confirmed by molecular analysis, which evidenced composite WFS1 heterozygous mutations inherited from both their mother and father. Ophthalmologists should be aware of the possibility of Wolfram syndrome when diagnosing optic atrophy in diabetic children.

Access of children and adolescents with type 1 diabetes to insulin pump therapy has greatly increased in France since 2001.

AIM: Insulin pump therapy is an emerging option in the management of type 1 diabetes (T1D), but it often remains unused. For this reason, in 2007, a French national survey was carried out to update the frequency of insulin pump use in the paediatric population compared with a previous survey done in 2001. METHODS: The present survey was performed in hospital departments involved in paediatric diabetes management (n = 67) and in adult departments involved in adolescent diabetes management (n = 113). The number of T1D children (age < 18 years) treated in each department, with or without the use of an insulin pump, and the number of insulin pump therapies initiated during the previous year were collected. RESULTS: A total of 60 paediatric and 28 adult centres responded, involving 9073 T1D children and adolescents (93% in paediatric departments). Of these patients, 1461 (16%) were treated by insulin pump, 89% of which were managed in paediatric centres. However, pump use was more frequent in adult than in paediatric centres (32% versus 18%, respectively). Also, 38% of insulin pumps were initiated during the year prior to the survey. In addition, in 2001, 140 children were treated with insulin pump in 13 paediatric centres (versus 56 centres in 2007). CONCLUSION: The number of centres using insulin pump therapy for diabetic children and the number of children treated by insulin pump were increased fourfold and 10-fold, respectively, from 2001 to 2007, indicating greater access to pump therapy in the French paediatric population. The present survey is still ongoing to evaluate the decision-making criteria that influence the initiation of insulin pump therapy in T1D paediatric patients.

[Progression of diabetic retinopathy during pregnancy: a retrospective analysis of a series of 77 consecutive patients]. / Progression de la rétinopathie diabétique chez les femmes enceintes : étude rétrospective monocentrique d'une série de 77 patientes consécutives.

INTRODUCTION: The aim of this study was to assess diabetic retinopathy progression during pregnancy and to determine the predictive factors of this progression. PATIENTS AND METHODS: Monocentric retrospective study including 77 consecutive diabetic women submitted to a multidisciplinary medical follow-up during pregnancy with at least one ophthalmologic examination per trimester with ocular fundus photographs. RESULTS: Diabetic retinopathy was evidenced in 21 (27.3%) of the patients during the first trimester (no proliferative form), in 22 women (28.6%) during the second (two proliferative forms), and 24 (31.2%) during the third (two proliferative forms). Progression of at least 1 grade was evidenced in four patients from the first to the second trimester, in three from the second to the third, and finally in seven patients during the overall follow-up period. Two patients showed progression to a proliferative form from the first to the second quarter. We failed to identify any predictive factor of diabetic retinopathy progression except when combining prior systemic hypertension and pregnancy-induced hypertension (p<0.03). CONCLUSION: The results of our study confirm that diabetic retinopathy progression is uncommon during pregnancy, especially if diabetic retinopathy is absent or mild at the beginning. Optimal blood sugar levels and blood pressure check-ups play a major role in preventing diabetic retinopathy progression. Collaborative medical follow-up can minimize ophthalmologic impairment during pregnancy.

Impact of postprandial and fasting glucose concentrations on HbA1c in patients with type 2 diabetes.

AIM: This study aimed to assess the relative contributions of postprandial and fasting glucose concentrations to overall hyperglycaemia. METHODS: Patients with type 2 diabetes (n=973) carried out self-monitored blood glucose (SMBG) profiles on entry into the European Exenatide (EUREXA) trial. Glucose area under the curve was calculated for postprandial excursions (AUC(ppg)) and total daytime concentrations >6.1 mmol/L (AUC(total)), as well as for the percentage of glycaemia due to postprandial excursions (%(ppg)). In addition, OGTT scores were assessed for each patient. Results were evaluated according to defined HbA(1c) categories. RESULTS: There was a significant linear relationship between HbA(1c) and the derived variables of AUC(ppg), AUC(total) and %(ppg) (P<0.001 for each), with explained variance greatest for AUC(total) (r(2)=37.4%). AUC(ppg) increased only slightly up to an HbA(1c) of 7.0%, but showed a steeper increase in higher HbA(1c) categories. Also, the increase in AUC(total) with increasing HbA(1c) was much more pronounced. As a result, the postprandial glucose excursion as a proportion of total glucose (%(ppg)) decreased across HbA(1c) categories from 61.0% at HbA(1c)<6.5% to 22.0% at HbA(1c)≥9.0%. HOMA-IR remained virtually unchanged through all HbA(1c) categories, while HOMA-B showed no large changes up to HbA(1c) 7.0%, but then decreased at higher HbA(1c) values. The ΔI30/ΔG30 ratio decreased in the HbA(1c) 7.0-7.9% category, but did not change greatly at higher HbA(1c) categories. CONCLUSION: With increasing HbA(1c), there was a decrease in the contribution of postprandial hyperglycaemia to total glycaemia, and fasting hyperglycaemia became more important. This is consistent with impaired insulin release, particularly first-phase release, at higher HbA(1c) levels.

When to treat a diabetic patient using an external insulin pump. Expert consensus. Société francophone du diabète (ex ALFEDIAM) 2009.

For years, external insulin pumps have enjoyed proven efficacy as an intensive diabetes treatment to improve glycaemic control and reduce hypoglycaemia. Since the last ALFEDIAM guidelines in 1995, however, basal-bolus treatment using a combination of long- and short-acting insulin analogues have emerged and could challenge, at a lower cost, the efficacy of pumps using rapid-acting insulin analogues, considered the 'gold standard' of insulin treatment. Nevertheless, given its theoretical and practical advantages, some patients will derive more benefit from pump treatment. These cases have been carefully evaluated in the literature by a panel of experts appointed by ALFEDIAM to determine the indications for pump treatment. In patients with type 1 diabetes, persistent elevated HbA(1c) despite multiple daily injections (MDI), and repeated hypoglycaemia and high glycaemic variability, represent the most validated indications. In patients with type 2 diabetes, pump treatment may be indicated in cases of MDI failure to achieve HbA(1c) targets. Absolute contraindications are rare, and comprise severe psychiatric disorders, rapidly progressing ischaemic or proliferative retinopathy before laser treatment and exposure to high magnetic fields. Relative contraindications are mostly related to the patient's lack of compliance or inability to cope with the treatment, and need to be evaluated individually to clearly assess the benefit/risk ratio for the given patient. However, as these conditions are progressive, there should also be annual reassessment of the appropriateness of pump treatment. Specific education on pump treatment initially and throughout the follow-up, delivered by experienced medical and paramedical teams, are the best guarantees of treatment efficacy and safety.

The clinical variability of maternally inherited diabetes and deafness is associated with the degree of heteroplasmy in blood leukocytes.

CONTEXT: Maternally inherited diabetes and deafness (MIDD) is a rare form of diabetes with a matrilineal transmission, sensorineural hearing loss, and macular pattern dystrophy due to an A to G transition at position 3243 of mitochondrial DNA (mtDNA) (m.3243A>G). The phenotypic heterogeneity of MIDD may be the consequence of different levels of mutated mtDNA among mitochondria in a given tissue. OBJECTIVE: The aim of the present study was thus to ascertain the correlation between the severity of the phenotype in patients with MIDD and the level of heteroplasmy in the blood leukocytes. PARTICIPANTS: The GEDIAM prospective multicenter register was initiated in 1995. Eighty-nine Europid patients from this register, with MIDD and the mtDNA 3243A>G mutation, were included. Patients with MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) or with mitochondrial diabetes related to other mutations or to deletions of mtDNA were excluded. RESULTS: A significant negative correlation was found between levels of heteroplasmy and age of the patients at the time of sampling for molecular analysis, age at the diagnosis of diabetes, and body mass index. After adjustment for age at sampling for molecular study and gender, the correlation between heteroplasmy levels and age at the diagnosis of diabetes was no more significant. The two other correlations remained significant. A significant positive correlation between levels of heteroplasmy and HbA(1c) was also found and remained significant after adjustment for age at molecular sampling and gender. CONCLUSIONS: These results support the hypothesis that heteroplasmy levels are at least one of the determinants of the severity of the phenotype in MIDD.