Type 2 diabetes subgroups and response to glucose-lowering therapy: Results from the EDICT and Qatar studies

AIM

To examine the efficacy of glucose-lowering medications in subgroups of patients with type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS

Cluster analysis was performed in participants in the Efficacy and Durability of Initial Combination Therapy for Type 2 Diabetes (EDICT) study and the Qatar study using age, body mass index (BMI), glycated haemoglobin (HbA1c), and homeostatic model assessment of insulin resistance (HOMA-IR) and beta-cell function (HOMA-β). Participants also underwent an oral glucose tolerance test with measurement of plasma glucose, insulin and C-peptide concentrations to derive independent measures of insulin secretion and insulin sensitivity. The response to glucose-lowering therapies (change in HbA1c) was measured in each participant cluster for 3 years.

RESULTS

Three distinct and comparable clusters/groups of T2DM patients were identified in both the EDICT and Qatar studies. Participants in Group 1 had the highest HbA1c and manifested severe insulin deficiency. Participants in Group 3 had comparable insulin sensitivity to those in Group 1 but better beta-cell function and better glucose control. Participants in Group 2 had the highest BMI with severe insulin resistance accompanied by marked hyperinsulinaemia, which was primarily attributable to decreased insulin clearance. Unexpectedly, participants in Group 1 had better response to combination therapy with pioglitazone plus exenatide than with insulin therapy or metformin sequentially followed by glipizide and basal insulin, while participants in Group 2 responded equally well to both therapies despite very severe insulin resistance.

CONCLUSION

Distinct metabolic phenotypes characterize different T2DM clusters and differential responses to glucose-lowering therapies. Participants with severe insulin deficiency respond better to agents that preserve beta-cell function, while, surprisingly, patients with severe insulin resistance did not respond favourably to insulin sensitizers.

Insulin resistance limits corneal nerve regeneration in patients with type 2 diabetes undergoing intensive glycemic control

AIMS/INTRODUCTION

This study aimed to investigate whether insulin resistance (IR) in individuals with type 2 diabetes undergoing intensive glycemic control determines the extent of improvement in neuropathy.

MATERIALS AND METHODS

This was an exploratory substudy of an open-label, randomized controlled trial of individuals with poorly controlled type 2 diabetes treated with exenatide and pioglitazone or insulin to achieve a glycated hemoglobin <7.0% (<53 mmol/mol). Baseline IR was defined using homeostasis model assessment of IR, and change in neuropathy was assessed using corneal confocal microscopy.

RESULTS

A total of 38 individuals with type 2 diabetes aged 50.2 ± 8.5 years with (n = 25, 66%) and without (n = 13, 34%) IR were studied. There was a significant decrease in glycated hemoglobin (P < 0.0001), diastolic blood pressure (P < 0.0001), total cholesterol (P < 0.01) and low-density lipoprotein (P = 0.05), and an increase in bodyweight (P < 0.0001) with treatment. Individuals with homeostasis model assessment of IR <1.9 showed a significant increase in corneal nerve fiber density (P ≤ 0.01), length (P ≤ 0.01) and branch density (P ≤ 0.01), whereas individuals with homeostasis model assessment of IR ≥1.9 showed no change. IR was negatively associated with change in corneal nerve fiber density after adjusting for change in bodyweight (P < 0.05).

CONCLUSIONS

Nerve regeneration might be limited in individuals with type 2 diabetes and IR undergoing treatment with pioglitazone plus exenatide or insulin to improve glycemic control.

Painful diabetic neuropathy is associated with increased nerve regeneration in patients with type 2 diabetes undergoing intensive glycemic control

AIMS/INTRODUCTION

Painful diabetic peripheral neuropathy (pDPN) is associated with small nerve fiber degeneration and regeneration. This study investigated whether the presence of pDPN might influence nerve regeneration in patients with type 2 diabetes undergoing intensive glycemic control.

MATERIALS AND METHODS

This exploratory substudy of an open-label randomized controlled trial undertook the Douleur Neuropathique en 4 questionnaire and assessment of electrochemical skin conductance, vibration perception threshold and corneal nerve morphology using corneal confocal microscopy in participants with and without pDPN treated with exenatide and pioglitazone or basal-bolus insulin at baseline and 1-year follow up, and 18 controls at baseline only.

RESULTS

Participants with type 2 diabetes, with (n = 13) and without (n = 28) pDPN had comparable corneal nerve fiber measures, electrochemical skin conductance and vibration perception threshold at baseline, and pDPN was not associated with the severity of DPN. There was a significant glycated hemoglobin reduction (P < 0.0001) and weight gain (P < 0.005), irrespective of therapy. Participants with pDPN showed a significant increase in corneal nerve fiber density (P < 0.05), length (P < 0.0001) and branch density (P < 0.005), and a decrease in the Douleur Neuropathique en 4 score (P < 0.01), but no change in electrochemical skin conductance or vibration perception threshold. Participants without pDPN showed a significant increase in corneal nerve branch density (P < 0.01) and no change in any other neuropathy measures. A change in the severity of painful symptoms was not associated with corneal nerve regeneration and medication for pain.

CONCLUSIONS

This study showed that intensive glycemic control is associated with greater corneal nerve regeneration and an improvement in the severity of pain in patients with painful diabetic neuropathy.

Combination therapy with pioglitazone/exenatide improves beta-cell function and produces superior glycaemic control compared with basal/bolus insulin in poorly controlled type 2 diabetes: A 3-year follow-up of the Qatar study

AIM

To examine the long-term efficacy of thiazolidinedione plus a glucagon-like peptide-1 receptor agonist versus basal-bolus insulin on glycaemic control and beta-cell function in patients with poorly controlled type 2 diabetes (T2D) on metformin plus sulphonylurea.

MATERIALS AND METHODS

Three hundred and thirty-one patients with poorly controlled T2D were recruited over 3 years and were followed for an additional year. Subjects received a 75 g oral glucose tolerance test (OGTT) at baseline and at study end. After completing the baseline OGTT, subjects were randomized to receive either pioglitazone plus weekly exenatide (combination therapy) or basal/bolus insulin (insulin therapy) to maintain an HbA1c of less than 7.0%. The primary outcome of the study was the difference in HbA1c at study end between the two treatment groups.

RESULTS

Both therapies caused a robust decrease in HbA1c. However, combination therapy caused a greater decrement (-1.1%, P < .0001) than insulin therapy, and more subjects in the combination therapy group (86%) achieved the American Diabetes Association goal of glycaemic control (HbA1c < 7.0%) than those in the insulin therapy group (44%) (P < .0001). Both therapies improved insulin secretion. However, the improvement in insulin secretion with combination therapy was 2.5-fold greater (P < .001) than with insulin therapy (50%). Insulin therapy caused more weight gain and hypoglycaemia.

CONCLUSION

Both combination therapy and insulin therapy effectively reduced HbA1c in poorly controlled T2D on multiple oral agents. However, combination therapy produced a greater improvement in insulin secretion and decrease in HbA1c with a lower risk of hypoglycaemia.

Effect of treatment with exenatide and pioglitazone or basal-bolus insulin on diabetic neuropathy: a substudy of the Qatar Study

INTRODUCTION

To assess the effect of exenatide and pioglitazone or basal-bolus insulin on diabetic peripheral neuropathy (DPN) in patients with poorly controlled type 2 diabetes (T2D).

RESEARCH DESIGN AND METHODS

This is a substudy of the Qatar Study, an open-label, randomized controlled trial. 38 subjects with poorly controlled T2D were studied at baseline and 1-year follow-up and 18 control subjects were assessed at baseline only. A combination of exenatide (2 mg/week) and pioglitazone (30 mg/day) or glargine with aspart insulin were randomly assigned to patients to achieve an HbA1c <53 mmol/mol (<7%). DPN was assessed with corneal confocal microscopy (CCM), DN4, vibration perception and sudomotor function.

RESULTS

Subjects with T2D had reduced corneal nerves, but other DPN measures were comparable with the control group. In the combination treatment arm (n=21), HbA1c decreased by 35.2 mmol/mol (3.8 %) (p<0.0001), body weight increased by 5.6 kg (p<0.0001), corneal nerve branch density increased (p<0.05), vibration perception worsened (p<0.05), and DN4 and sudomotor function showed no change. In the insulin treatment arm, HbA1c decreased by 28.7 mmol/mol (2.7 %) (p<0.0001), body weight increased by 4.6 kg (p<0.01), corneal nerve branch density and fiber length increased (p≤0.01), vibration perception improved (p<0.01), and DN4 and sudomotor function showed no change. There was no association between the change in CCM measures with change in HbA1c, weight or lipids.

CONCLUSIONS

Treatment with exenatide and pioglitazone or basal-bolus insulin results in corneal nerve regeneration, but no change in neuropathic symptoms or sudomotor function over 1 year.

Pioglitazone prevents the increase in plasma ketone concentration associated with dapagliflozin in insulin-treated T2DM patients: Results from the Qatar Study

Because of the unique mechanism of action of sodium-glucose co-transport inhibitors (SGLT2i), which is independent of insulin secretion and insulin action, members of this class of drugs effectively lower plasma glucose concentration when used in combination with all other antidiabetic agents, including insulin. Increased plasma ketone concentration has been reported in association with SGLT2i initiation, which, under certain clinical conditions, has developed into diabetic ketoacidosis. The daily insulin dose often is reduced at the time of initiating SGLT2i therapy in insulin-treated patients to avoid hypoglycaemia. However, reduction of insulin dose can increase the risk of ketoacidosis. In the present study, we examined the effect of the addition of dapagliflozin plus pioglitazone on plasma ketone concentration in insulin-treated T2DM patients and compared the results to the effect of dapagliflozin alone. A total of 18 poorly controlled, insulin-treated T2DM participants in the Qatar Study received dapagliflozin (10 mg) plus pioglitazone (30 mg), and 10 poorly controlled non-insulin-treated T2DM patients received dapagliflozin (10 mg) alone for 4 months. Dapagliflozin plus pioglitazone produced a robust decrease in HbA1c (-1.4%) and resulted in a 50% reduction in daily insulin dose, from 133 to 66 units, while dapagliflozin alone caused a 0.8% reduction in HbA1c. Dapagliflozin caused a four-fold increase in fasting plasma ketone concentration, while the combination of pioglitazone plus dapagliflozin was not associated with a significant increase (0.13 vs 0.15 mM) in plasma ketone concentration or in risk of hypoglycaemia. These results demonstrate that the addition of pioglitazone to dapagliflozin prevents the increase in plasma ketone concentration associated with SGLT2i therapy.

Insulin secretion predicts the response to therapy with exenatide plus pioglitazone, but not to basal/bolus insulin in poorly controlled T2DM patients: Results from the Qatar study

The present study aims to identify predictors for response to combination therapy with pioglitazone plus exenatide vs basal/bolus insulin therapy in T2DM patients who are poorly controlled with maximum/near-maximum doses of metformin plus a sulfonylurea. Participants in the Qatar study received a 75-g OGTT with measurement of plasma glucose, insulin and C-peptide concentration at baseline and were then randomized to receive either treatment with pioglitazone plus exenatide or basal/bolus insulin therapy for one year. Insulin secretion measured with plasma C-peptide concentration during the OGTT was the strongest predictor of response to combination therapy (HbA1c ≤ 7.0%) with pioglitazone plus exenatide. A 54% increase in 2-hour plasma C-peptide concentration above the fasting level identified subjects who achieved the glycaemic goal (HbA1c < 7.0%) with 82% sensitivity and 79% specificity. Only baseline HbA1c was a predictor of response to basal/bolus insulin therapy. Thus, the increment in 2-hour plasma C-peptide concentration above the fasting level provides a useful tool to identify poorly controlled T2DM patients who can achieve glycaemic control without insulin therapy, and thereby, can be used to individualize antihyperglycaemic therapy in poorly controlled T2DM patients.

Efficacy of Exenatide Plus Pioglitazone Vs Basal/Bolus Insulin in T2DM Patients With Very High HbA1c

OBJECTIVE

To examine the efficacy and safety of combination therapy with exenatide plus pioglitazone vs basal/bolus insulin in patients with poorly controlled type 2 diabetes mellitus (T2DM) with very high hemoglobin A1c (HbA1c) (>10%) receiving sulfonylurea plus metformin and with a long duration of disease.

DESIGN AND PARTICIPANTS

Participants (n = 101) in the Qatar Study with very poor glycemic control (HbA1c >10%) and a long duration of diabetes (10.9 years) receiving maximum/near-maximum doses of sulfonylurea plus metformin were randomly assigned to receive pioglitazone plus weekly exenatide (combination therapy), or basal plus prandial insulin (insulin therapy), to maintain HbA1c <7.0%.

RESULTS

Baseline HbA1c was 11.5% ± 0.2% and 11.2% ± 0.2% (P = not significant) in combination therapy and insulin therapy groups, respectively. At 6 months, combination therapy caused a robust decrease in HbA1c to 6.7% ± 0.1% (∆ = -4.8%) compared with 7.4% ± 0.1% (∆ = -3.8%) in subjects receiving insulin therapy. Combination therapy was effective in lowering the HbA1c independent of sex, ethnicity, or body mass index. Subjects in the insulin therapy group experienced significantly greater weight gain and a 2.5-fold higher rate of hypoglycemia compared with patients receiving combination therapy.

CONCLUSION

Exenatide/pioglitazone combination therapy is an effective and safe therapeutic option in patients with poorly controlled T2DM receiving metformin plus sulfonylurea with very high HbA1c (>10%).

Combination Therapy With Exenatide Plus Pioglitazone Versus Basal/Bolus Insulin in Patients With Poorly Controlled Type 2 Diabetes on Sulfonylurea Plus Metformin: The Qatar Study

OBJECTIVE

The Qatar Study was designed to examine the efficacy of combination therapy with exenatide plus pioglitazone versus basal/bolus insulin in patients with long-standing poorly controlled type 2 diabetes mellitus (T2DM) on metformin plus a sulfonylurea.

RESEARCH DESIGN AND METHODS

The study randomized 231 patients with poorly controlled (HbA_1c >7.5%, 58 mmol/mol) T2DM on a sulfonylurea plus metformin to receive 1) pioglitazone plus weekly exenatide (combination therapy) or 2) basal plus prandial insulin (insulin therapy) to maintain HbA_1c <7.0% (53 mmol/mol).

RESULTS

After a mean follow-up of 12 months, combination therapy caused a robust decrease in HbA_1c from 10.0 ± 0.6% (86 ± 5.2 mmol/mol) at baseline to 6.1 ± 0.1% (43 ± 0.7 mmol/mol) compared with 7.1 ± 0.1% (54 ± 0.8 mmol/mol) in subjects receiving insulin therapy. Combination therapy was effective in lowering the HbA_1c independent of sex, ethnicity, BMI, or baseline HbA_1c. Subjects in the insulin therapy group experienced significantly greater weight gain and a threefold higher rate of hypoglycemia than patients in the combination therapy group.

CONCLUSIONS

Combination exenatide/pioglitazone therapy is a very effective and safe therapeutic option in patients with long-standing poorly controlled T2DM on metformin plus a sulfonylurea.